To solve the problem that a landing door switch for detecting the door opening and closing condition to determine whether an elevator can be operated or not stops the elevator in an emergency and locks passengers in the elevator by determining that the door is opened by a contact failure and the wrong operation when an impact is applied to the door.

A light projector means 1 and a light receiver means 2 are provided in specified floors at a building side so that a photoelectric beam from the light projector means 1 reaches the light receiver means 2 through the predetermined optical path 21, and a second means is provided to detect opening and closing of the landing floor doors 3a and 3b with a shutoff of the optical path 21 when the landing floor doors 3a and 3b between the light projector means 1 and the light receiver means 2 are opened. In the ordinary operation, door opening and closing condition is detected by a detecting means 6 for the landing floor doors 3a and 3b, and when the first detecting means detects the opening condition and the second detecting means detects the closing condition in the lock-in condition, the rescue operation is performed.