An endoscope system includes: an optical system； an actuator configured to move at least an optical element of the optical system. along an optical axis direction； a driving signal generator configured to generate and supply a driving signal for driving the actuator； a transmission cable electrically connecting the actuator and the driving signal generator； a detector configured to detect magnitude of the driving signal through the transmission cable； and a processor including hardware, the processor being configured to supply the driving signal with an initial driving voltage value to the actuator for a predetermined time, calculate a combined resistance value including a resistance value of the transmission cable and a resistance value of the actuator, based on at least the detected magnitude of the driving signal, calculate a driving voltage of the actuator, based on the calculated combined resistance value and a preset rated current value of the actuator, and cause a storage to record the calculated driving voltage.
