A bend information computation apparatus includes a light source, a first light guide, a detection target, a second light guide, a switching member, a driver, a detector, a generator, and a bend information arithmetic operator. The detector is configured to detect first and second spectrum change. The generator is configured to calculate, based on the second spectrum change, suppression information. The bend information arithmetic operator is configured to calculate change information based on the first spectrum change and the suppression information and to compute bend information based on the change information.