A personal authentication device includes an infrared ray emitter that emits infrared rays, an infrared camera that captures an infrared image, a status signal outputter that outputs a signal related to a status of the personal authentication device or the status of surroundings of the personal authentication device, and a controller. The controller determines whether or not there is a predetermined change in the status of the personal authentication device or the status of the surroundings of the personal authentication device based on a signal output from the status signal outputter, and when there is the predetermined change, the controller drives the infrared ray emitter and the infrared camera, and performs a three-dimensional face authentication process based on the infrared image captured by the infrared camera.