An elevator derailment detecting device according to the present invention detects the opened and closed states of contacts at first and second safety relays 82 and 83 (steps S1 and S2). Since a first NO contact 82b is closed, a first NC contact 82c is opened, a second NO contact 83b is closed, and a second NC contact 83c is opened, it is determined that there is no circuit failure. Then, the opened and closed state of the contactless relay 84 is detected (step S3). When the contactless relay NO contact 84b is closed and the contactless relay NC contact 84c is opened, it is determined that the counterweight 21 of the elevator 11 is in a derailed state.