A head lamp device of a vehicle comprises a pair of lamp units arranged in a direction perpendicular to a forward and rearward direction of a vehicle body, each of the pair of lamp units including at least one light emitting element; and a lighting circuit unit which is supplied with electric power from a power supply and lights the at least one light emitting element, wherein at least a portion of the lighting circuit unit is disposed in a gap formed between the pair of lamp units in the direction in which the pair of lamp units are arranged.