The circuit may include bio-stimulating signal generating circuit which generates a bio-stimulating signal in a bio-stimulating mode, a bio-signal electrode which delivers the bio-stimulating signal generated in the bio-stimulating mode and receives a bio-signal in a bio-signal measuring mode, a switch block which is turned on when a voltage of the bio-stimulating signal is greater than a first reference voltage which is greater than a second reference voltage or lower than the second reference voltage, first and second resistors, and a bio-signal measuring circuit which measures voltage signals divided by the first and second resistors or measures a signal of the bio-signal electrode according to whether the switch block is turned on. The first and second resistors may be serially connected between the bio-signal electrode and the switch block, and divide a voltage of a signal of the bio-signal electrode when the switch block is turned on.