A camera module comprises a base, a lens joined to the base, a frame movably disposed on the base, an image detecting unit fixed to the frame and moving on the base via the frame, and a solenoid having a post moving between a first position and a second position. When the image detecting unit moves on the base via the frame, the post is in the first position and has no contact with the image detecting unit. When the image detecting unit moves on the base not via the frame, the post is in the second position and abuts the image detecting unit to position the image detecting unit.