An automatic focusing apparatus for use in a camera has an operating member which moves from a rest position to a depressed position. An actuating member is rotatably mounted on the operating member and a detecting member is mounted for movement from a first position to a second position and is biased normally into the first position. The actuating member enables the detecting member to move from the first to the second position in response to the movement of the operating member from the rest position to the depressed position and disengages from the detecting member when the operating member is in the depressed position to enable the detecting member to move from the second position to the first position under the action of its bias. A device produces an electric signal corresponding to the position of the detecting member and a focus scanning member is movable over its entire focus scanning range in response to the movement of the detecting member between its first and second positions. An electro-magnet is provided for stopping the movement of the detecting member during its movement from the second to the first position when the electro-magnet is actuated. A focus detecting module receives a signal from the device synchronously with the movement of the focus scanning member during the movement of the detecting member to the second position to determine the signal from the device corresponding to the in-focus position and for actuating the electro-magnet to stop the return movement of the detecting member to its first position when the signal from the device is equal to that determined for the in-focus position. In this way, the camera lens can be focused with reduced error.