A laser detector includes a latch and a semiconductor device including the same. The laser detector includes a latch configured to output an output signal and an inverted output signal and an initial value setting circuit configured to set an initial value of at least one of the output signal and the inverted output signal. The latch includes a first transistor controlled to be initially turned on by the initial value and a second transistor controlled to be initially turned off by the initial value. The second transistor has an active region having a lateral area that is greater than that of the first transistor.