To provide a vehicular headlight structured to increase a quantity of light reflected frontward from a light source and reduce the number of components without enlarging a projection lens.

This vehicular headlight 10 is equipped with the light source 11, a reflecting surface 12 concave frontward, and a convex projection lens 13 irradiating light from the light source and the reflecting surface by converging the light. The reflecting surface comprises an elliptical center region 12a reflecting light toward the projection lens and a peripheral region 12b disposed at its outside, the projection lens is equipped with a second lens 13a to diffuse light from the peripheral region of the reflecting surface in its surrounding, the second lens is formed as a diffusing prism lens 13 so that the rear surface on the light source side is formed as the concave surface of a high order to change light from the peripheral region of the reflecting surface to almost parallel light, and the front surface vertically refracts and horizontally diffuse the light.