PURPOSE: To confirm the call response even when an incandescent lamp fails by providing an auxiliary display section displaying registration confirmation only while a call button is pressed.

CONSTITUTION: When a user touches a contact plate 1 on the surface of a call button, the electrostatic capacity of a human body is applied to an oscillating circuit 3 via an electrode 2, the oscillation condition is collapsed, and oscillation is stopped. The signal is taken out through a filter 4 and a comparator 5, a pulse is outputted by the filter 4 and a one-shot circuit 6, a call signal is outputted via a photo-coupler 7, and a call is registered. An incandescent lamp 8 and a LED 9 fitted to a control board are lighted by the lamp lighting command. The LED 9 is concurrently used in addition to the incandescent lamp 8 as light emitting elements. Even when the incandescent lamp 8 fails, the LED 9 is lighted while the user touches the call button, thus the user can confirm call registration.