A speed measuring apparatus for a conveyor line may include a lighting unit mounted to one side of the conveyor line with a bracket, a coupling module coupled to an upper side of the lighting unit, the coupling module having coupling portions formed on both sides of an upper side thereof, respectively, a camera having a lens unit mounted between the coupling portions to face downward for taking a picture of an image of the object on the conveyor line under operation, a lens rotation device having a motor mounted to end portions of, and between, the coupling portions for selective positioning of a magnifying lens matched to the lens unit of the camera as the motor may be driven, and a controller for controlling operation of the lens rotation device and comparing images taken by the camera at different times to determine a speed of the object.