diff --git a/CHANGES b/CHANGES
index 5b7550bcc..f48956201 100644
--- a/CHANGES
+++ b/CHANGES
@@ -72,6 +72,10 @@ Features added
 * math: Add hyperlink marker to each equations in HTML output
 * Add new theme ``nonav`` that doesn't include any navigation links.
   This is for any help generator like qthelp.
+* #2680: `sphinx.ext.todo` now emits warnings if `todo_emit_warnings` enabled.
+  Also, it emits an additional event named `todo-defined` to handle the TODO
+  entries in 3rd party extensions.
+
 
 Bugs fixed
 ----------
diff --git a/doc/ext/todo.rst b/doc/ext/todo.rst
index a809bc665..09abfa9b8 100644
--- a/doc/ext/todo.rst
+++ b/doc/ext/todo.rst
@@ -34,6 +34,13 @@ There is also an additional config value:
    If this is ``True``, :rst:dir:`todo` and :rst:dir:`todolist` produce output,
    else they produce nothing.  The default is ``False``.
 
+.. confval:: todo_emit_warnings
+
+   If this is ``True``, :rst:dir:`todo` emits a warning for each TODO entries.
+   The default is ``False``.
+
+   .. versionadded:: 1.5
+
 .. confval:: todo_link_only
 
    If this is ``True``, :rst:dir:`todolist` produce output without file path and line,
@@ -41,3 +48,11 @@ There is also an additional config value:
 
    .. versionadded:: 1.4
 
+autodoc provides the following an additional event:
+
+.. event:: todo-defined (app, node)
+
+   .. versionadded:: 1.5
+
+   Emitted when a todo is defined. *node* is the defined ``sphinx.ext.todo.todo_node``
+   node.
diff --git a/sphinx/ext/todo.py b/sphinx/ext/todo.py
index a853ec93c..f3b526ce6 100644
--- a/sphinx/ext/todo.py
+++ b/sphinx/ext/todo.py
@@ -70,6 +70,8 @@ def process_todos(app, doctree):
     if not hasattr(env, 'todo_all_todos'):
         env.todo_all_todos = []
     for node in doctree.traverse(todo_node):
+        app.emit('todo-defined', node)
+
         try:
             targetnode = node.parent[node.parent.index(node) - 1]
             if not isinstance(targetnode, nodes.target):
@@ -86,6 +88,9 @@ def process_todos(app, doctree):
             'target': targetnode,
         })
 
+        if env.config.todo_emit_warnings:
+            env.warn_node("TODO entry found: %s" % node[1].astext(), node)
+
 
 class TodoList(Directive):
     """
@@ -187,8 +192,10 @@ def depart_todo_node(self, node):
 
 
 def setup(app):
+    app.add_event('todo-defined')
     app.add_config_value('todo_include_todos', False, 'html')
     app.add_config_value('todo_link_only', False, 'html')
+    app.add_config_value('todo_emit_warnings', False, 'html')
 
     app.add_node(todolist)
     app.add_node(todo_node,
diff --git a/tests/roots/test-ext-todo/bar.rst b/tests/roots/test-ext-todo/bar.rst
new file mode 100644
index 000000000..6804a68c1
--- /dev/null
+++ b/tests/roots/test-ext-todo/bar.rst
@@ -0,0 +1,4 @@
+bar
+===
+
+.. todo:: todo in bar
diff --git a/tests/roots/test-ext-todo/conf.py b/tests/roots/test-ext-todo/conf.py
new file mode 100644
index 000000000..c67a86c5a
--- /dev/null
+++ b/tests/roots/test-ext-todo/conf.py
@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+
+extensions = ['sphinx.ext.todo']
+master_doc = 'index'
diff --git a/tests/roots/test-ext-todo/foo.rst b/tests/roots/test-ext-todo/foo.rst
new file mode 100644
index 000000000..269199977
--- /dev/null
+++ b/tests/roots/test-ext-todo/foo.rst
@@ -0,0 +1,4 @@
+foo
+===
+
+.. todo:: todo in foo
diff --git a/tests/roots/test-ext-todo/index.rst b/tests/roots/test-ext-todo/index.rst
new file mode 100644
index 000000000..6b95f73fd
--- /dev/null
+++ b/tests/roots/test-ext-todo/index.rst
@@ -0,0 +1,9 @@
+test for sphinx.ext.todo
+========================
+
+.. toctree::
+
+   foo
+   bar
+
+.. todolist::
diff --git a/tests/test_ext_todo.py b/tests/test_ext_todo.py
new file mode 100644
index 000000000..269a8a2be
--- /dev/null
+++ b/tests/test_ext_todo.py
@@ -0,0 +1,85 @@
+# -*- coding: utf-8 -*-
+"""
+    test_ext_todo
+    ~~~~~~~~~~~~~
+
+    Test sphinx.ext.todo extension.
+
+    :copyright: Copyright 2007-2016 by the Sphinx team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+import re
+from util import with_app
+
+
+@with_app('html', testroot='ext-todo', freshenv=True,
+          confoverrides={'todo_include_todos': True, 'todo_emit_warnings': True})
+def test_todo(app, status, warning):
+    todos = []
+
+    def on_todo_defined(app, node):
+        todos.append(node)
+
+    app.connect('todo-defined', on_todo_defined)
+    app.builder.build_all()
+
+    # check todolist
+    content = (app.outdir / 'index.html').text()
+    html = ('<p class="first admonition-title">Todo</p>\n'
+            '<p class="last">todo in foo</p>')
+    assert re.search(html, content, re.S)
+
+    html = ('<p class="first admonition-title">Todo</p>\n'
+            '<p class="last">todo in bar</p>')
+    assert re.search(html, content, re.S)
+
+    # check todo
+    content = (app.outdir / 'foo.html').text()
+    html = ('<p class="first admonition-title">Todo</p>\n'
+            '<p class="last">todo in foo</p>')
+    assert re.search(html, content, re.S)
+
+    # check emitted warnings
+    assert 'WARNING: TODO entry found: todo in foo' in warning.getvalue()
+    assert 'WARNING: TODO entry found: todo in bar' in warning.getvalue()
+
+    # check handled event
+    assert len(todos) == 2
+    assert set(todo[1].astext() for todo in todos) == set(['todo in foo', 'todo in bar'])
+
+
+@with_app('html', testroot='ext-todo', freshenv=True,
+          confoverrides={'todo_include_todos': False, 'todo_emit_warnings': True})
+def test_todo_not_included(app, status, warning):
+    todos = []
+
+    def on_todo_defined(app, node):
+        todos.append(node)
+
+    app.connect('todo-defined', on_todo_defined)
+    app.builder.build_all()
+
+    # check todolist
+    content = (app.outdir / 'index.html').text()
+    html = ('<p class="first admonition-title">Todo</p>\n'
+            '<p class="last">todo in foo</p>')
+    assert not re.search(html, content, re.S)
+
+    html = ('<p class="first admonition-title">Todo</p>\n'
+            '<p class="last">todo in bar</p>')
+    assert not re.search(html, content, re.S)
+
+    # check todo
+    content = (app.outdir / 'foo.html').text()
+    html = ('<p class="first admonition-title">Todo</p>\n'
+            '<p class="last">todo in foo</p>')
+    assert not re.search(html, content, re.S)
+
+    # check emitted warnings
+    assert 'WARNING: TODO entry found: todo in foo' in warning.getvalue()
+    assert 'WARNING: TODO entry found: todo in bar' in warning.getvalue()
+
+    # check handled event
+    assert len(todos) == 2
+    assert set(todo[1].astext() for todo in todos) == set(['todo in foo', 'todo in bar'])