A projector has a disassembling lock for preventing the lamp cover from being disassembled when the projector is secured to a ceiling. The disassembling lock includes a sleeve, a latching rod, a stop block, and a coil spring. The sleeve is secured in the projector and has a first sleeve portion and a second sleeve portion. The latching rod has a first rod portion, a second rod portion, and a flange formed between the first rod portion and the second rod portion, the flange is slidable inside the first sleeve portion. The stop block is fixed in a distal end of the first sleeve portion away from the second sleeve portion, the stop block defines a hole for the first rod portion sliding to the lamp cover. The coil spring is coiled around the first rod portion and held between the flange and the stop block.