PROBLEM TO BE SOLVED: To suppress degradation in followability of a light irradiation direction for a shape of a traffic lane in an irradiation direction control technology for executing lane following control of changing a light irradiation direction according to the shape of the traffic lane.SOLUTION: In an irradiation direction control device, an irradiation direction control section executes lane following control for controlling a light irradiation direction to follow in the shape of the traffic lane when lane following conditions are satisfied and, when the lane following conditions are not satisfied, avoids execution of the lane following control and executes angle following control for controlling the light irradiation direction to follow a steering angle. When a vehicle speed is lower than a reference speed and a lane curvature is smaller than a reference curvature, the irradiation direction control section determines that there is no necessity for improving followability of a target irradiation direction and determines whether or not the lane following conditions are satisfied in a first cycle. When a vehicle speed is higher than the reference speed or the lane curvature is larger than the reference curvature, the irradiation direction control section determines that there is necessity for improving followability of the target irradiation direction and determines whether or not the lane following conditions are satisfied in a second cycle that is shorter than the first cycle.