A light distribution-controlling device of a vehicle headlight includes headlight lamp bodies (2L, 2R), light distribution operation switches (8, 9) including a passing switch, a front detection unit (11) that detects an object in front of an own vehicle, a manual mode control unit (13) that controls the light distribution of the headlight lamp body based on a signal outputting from the light distribution operation switch, an auto mode control unit (14) 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 (7) 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 (15) 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 (16) that returns the control of the light distribution to the control by the auto mode control unit.