Vehicle lamp controller, vehicle lamp system, and vehicle lamp control method

A vehicle lamp controller (228R,228L,302), a vehicle lamp system, and a vehicle lamp control method are provided. The vehicle lamp system includes an acceleration sensor (316), a vehicle lamp (10), and the vehicle controller. The controller includes a receiver (228R1,228L1) configured to receive an acceleration information detected by the acceleration sensor (316), a control unit (228R2,228L2) configured to derive a vehicle longitudinal direction acceleration and a vehicle vertical direction acceleration from the acceleration information, and to generate a control signal for instructing an adjustment of an optical axis (O) of the vehicle lamp (10), based on a variation in a ratio between a temporal change amount of the vehicle longitudinal direction acceleration and a temporal change amount of the vehicle vertical direction acceleration during at least one of an acceleration and a deceleration of a vehicle (300), and a transmitter configured to transmit the control signal to an optical axis adjusting portion (236,226) of the vehicle lamp (10).