An information processing unit, such as a mobile phone, equipped with a fingerprint sensor and which reconciles size reduction with operability at a high level. A V-shaped groove is provided adjacent an operation panel, the V-shaped groove containing a first slope stretching away from the operation panel and slanting downward and a second slope stretching further away from the operation panel and slanting upward. The V-shaped groove may contain a fingerprint sweep sensor which detects a fingerprint on a finger moved along the first slope and the second slope.