Disclosed is a door closer of which the inside of a housing is made compact and thus is easily made smaller. The disclosed door closer is comprised so that movement of one end of a coil spring, which is relatively close to a link shaft, toward the link shaft inside of the housing is limited, and the other end of the coil spring, which is relatively far from the link shaft, moves toward the link shaft by being pushed by a piston base portion, thereby compressing the coil spring.