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. Adjacent to an operation panel is located a V-shaped groove which contains 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, where the V-shaped groove contains a fingerprint sweep sensor which detects a fingerprint on a finger moved along the first slope and the second slope.