This invention offers an LCD drive circuit that prevents conversion to a wrong duty driving state and an unintended display caused by taking in of serial data corresponding to the wrong duty driving state. The LCD drive circuit is provided with an LCD drive signal generation circuit that generates driving signals to turn LCD segments on and off based on serial data received by a serial data receiving circuit and is switchable between a ¼ duty driving state and a ⅓ duty driving state. The LCD drive circuit is also provided with a driving state setting circuit that sets the LCD drive signal generation circuit to the ¼ duty driving state based on identification data when the serial data receiving circuit receives the serial data corresponding to the ¼ duty driving state and thereafter forbids the LCD drive signal generation circuit to take in serial data corresponding to the ⅓ duty driving state when the serial data receiving circuit receives the serial data corresponding to the ⅓ duty driving state.