To solve a problem that a sense of incongruity is generated at a driver by an operation under a condition, that a visual field is ensured, such as a road fully equipped with a road illumination in a conventional variable light distribution head lamp system.

According to the present invention, in the variable light distribution head lamp system 1, a surrounding illuminance sensor 5 for detecting a surrounding illuminance is provided. In the case where an output level of the surrounding illuminance detection sensor is a predetermined value or more, a light distribution change means stops a function of at least one part. Therefore, for example, at twilight or under condition, that a visual field is ensured, such as a road fully equipped with a road illumination device, the variable light distribution head lamp system is operated and it is solved that a sense of incongruity is generated at a driver.