Light distribution-controlling device of vehicle headlight

A light distribution-controlling device of a vehicle headlight, comprising:

• a headlight lamp body that switches light distribution to any one of a low beam state and a high beam state;
• a light distribution operation switch that includes a passing switch having a momentary mechanism, and switches light distribution of the headlight lamp body by a driver's operation;
• a front detection unit that detects an object in front of an own vehicle;
• a manual mode control unit that controls the light distribution of the headlight lamp body based on a signal output from the light distribution operation switch;
• an auto mode control unit that controls the light distribution of the headlight lamp body based on a signal output from the front detection unit;
• an auto mode changeover switch that switches control of the light distribution of the headlight lamp body to control by the auto mode control unit by the driver's operation;
• a passing continuation-determining unit that determines whether a continuation time of an ON operation of the passing switch is more than or equal to a threshold continuation time;
• and
• an auto mode-returning unit that returns the control of the light distribution to the control by the auto mode control unit when the continuation time is determined to be more than or equal to the threshold continuation time by the passing continuation-determining unit after the control of the light distribution by the auto mode control unit is switched to control of the light distribution by the manual mode control unit by an operation on the light distribution operation switch in a case in which the auto mode changeover switch is in an ON state.