A drive circuit 1000 is provided with an input terminal and an output terminal configured to be coupled to an external device 2000; a drive signal generation circuit 400 configured to use a synchronizing signal that is input from the external device 2000 via the input terminal to perform signal generation processing to generate a drive signal that drives an electro-optical panel 10; a state signal generation circuit 510 configured to generate a state signal indicating an operating state of the drive signal generation circuit 400; a return signal generation circuit 520 configured to generate a return signal obtained by superimposing the state signal on the synchronizing signal; and the output circuit 2000 configured to output the return signal from output terminals 581 and 582 to the external device 2000.