Collision detection sensor and method

A collision detection sensor includes a light-emitting section (20), a fiber optics (3) which allows light emitted by the light-emitting section (20) to pass therethrough, a light-receiving section (21) which receives the light passing through the fiber optics (3) and performs photoelectric conversion, a filter (22) electrically connected to the light-emitting section (20) and having a time constant longer than a time constant of a collision signal produced at the time when the fiber optics (3) is deformed as a result of collision, and an energizing current adjustment section (23) for adjusting an energizing current flowing through the light-emitting section (20) based on a frequency component extracted by the filter (22).