To detect a customer approaching to a device with a compact and lightweight constitution without using any deflecting lens nor filter by using a proximity sensor which detects a moving object by means of an ultrasonic wave and also calculates the distance from the object.

A proximity sensor part 30 receives an ultrasonic wave from an ultrasonic wave transmitter and sends the pulse number of the ultrasonic wave to an IO control part 24. Based on the received pulse number, the part 24 calculates the transmission time and the distance from a customer. Then, a device is switched to an operable state from an idle state if it is judged that a customer is approaching to the device to operate it. Then, the part 24 sends the calculated distance set from the customer to a main control part 21. The part 21 controls a voice generation part 23 based on the received distance to reduce or increase the guiding voice volume when the said distance is small or large, respectively.