Grip sensor includes base material, sensor wire formed on base material, and sensor circuit electrically connected to an end of sensor wire. Sensor wire includes first wire portion on a side of sensor end, and a second wire portion on a side of power source end. In a state where base material is attached on a rim, second wire portion is disposed at an outer peripheral surface of the rim that is a site opposing a knee or thigh of a driver operating a steering wheel, and first wire portion is disposed at a front side and a rear side of the rim.