To efficiently assure forward visibility of a driver in a vehicular head lamp equipped with a reflector having a diffusion deflecting function.

An inner-shape in a near end part 12A2 of a lens front surface part 12A is set to a concave curved surface C which gradually increases the thickness of the lens front surface part 12A as the inner-shape approaches nearer to a leading portion 12B. As a result, a concave lens function is added to the near end part 12A2. Accordingly, even if shrinkage S is caused in a corner part 12C upon the formation of the lens, the near end part 12A2 is prevented from functioning as convex lens in advance. Disturbance by lens transmission of diffusion distribution of diffused reflecting light from a reflector is suppressed. Light stripes are prevented from occurring by the lens transmission. If no shrinkage S is generated in the corner portion 12C, the diffused reflecting light made incident on the end portion near part 12A2 is transmitted and diffused at a further large diffused angle by the concave lens action. Therefore, disturbance of the diffusion distribution and light stripes will not be generated.