A turning direction indicator controls the operation of a light source for turn signals and indicates a turning direction of the vehicle. Switch contacts are brought into electrical contact with each other, responsive to operation of an operating part. An angular velocity sensor detects an angular velocity of a vehicle turning, and outputs an angular velocity signal. A controller controls the output of a drive signal for causing operation of the light source, according to the electrical contact between the switch contacts and the angular velocity signal. The controller controls the output of the drive signal, according to the angular velocity signal, and a speed signal indicating a speed of the vehicle. The controller controls the output of the drive signal, according to the relation between the set threshold value and the angular velocity signal, and the relation between the angular velocity signal and the speed signal.