PURPOSE: To prevent an erroneous action so as to improve the operability of a steering wheel, by not closing an electric circuit for load even when the steering wheel becomes in contact with an operation part of switches during the turning of the steering wheel not less than a prescribed turning angle.

CONSTITUTION: A turn sensor section 5 has a turning base disk 5a that can turn together with the steering wheel 1, and a conductor 5c and a high resistor 5d are embedded in a helical guide groove 5b formed in said base disk 5a. The conductor 5c is arranged in a section corresponding to a prescribed turning angle of the wheel 1, and is connected with a positive power source. A contact needle 5e contacts while sliding with the conductor 5c and the high resistor 5d, is connected with a turn judging circuit section 6, and can output a signal when the wheel 1 is within the prescribed turning angle. According to the presence or absence of said signal the turn judging circuit section 6 controls signals sent through an encoding circuit section 3 and an optical coupler section 4 from various switches 2 provided to the wheel 1 so as to control the driving of the load 8 via a decoding circuit section 7.