Provided is a power transmitting device including an input side gear assembly that includes a single power input terminal and two power output terminals, an output side gear assembly that includes two power input terminals and a single power output terminal, the two power input terminals configured to operate using power received from the two power output terminals of the input side gear assembly, respectively, and a stopper module configured to block power to be transmitted through one of two power transmitting paths connecting the two power output terminals of the input side gear assembly and the two power input terminals of the output side gear assembly.