A projector type headlight comprising: a projection lens which is arranged on an optical axis, the optical axis extending in a longitudinal direction of a vehicle, the projection lens having a focal plane; and a light source unit which is arranged on a more rear side than a back side of the focal plane of the projection lens, wherein the projection lens is composed of two resin lenses (22, 24) which are arranged on the optical axis and include a first resin lens arranged more distant from the light source unit and a second resin lens arranged closer to the light source unit, wherein the first resin lens has a positive power, wherein the second resin lens has a lens face on a side opposite to the light source unit that is formed to be a face in which a change of a shape of the lens face is smaller than a change of a shape of a lens face in a side opposite to the light source unit on the first resin lens wherein the second resin lens has a wall thickness thinner than a wall thickness of the first resin lens, wherein the light source unit includes a light source and is configured so as to form a light source image that is emitted forward through the two resin lenses (22, 24) and forms a light distribution pattern including a boundary line between light and shade, substantially on the back side focal plane of the projection lens, characterized in that the second resin lens has a lens face having a positive power, and the second resin lens has a positive power, wherein the lens face having the positive power is arranged on a light source side, wherein a diffraction grating is provided on the lens face of the second resin lens on the side opposite to the light source unit, wherein the diffraction grating is formed to make the light of long wavelength out of the light emitted from the light source unit easier to be refracted than the light of short wavelength out of the light emitted from the light source unit to cancel chromatic aberration, which would otherwise occur if no diffraction grating were present, when the light is emitted from the light source unit and is emitted forward through a projection lens made of resin. a projection lens which is arranged on an optical axis, the optical axis extending in a longitudinal direction of a vehicle, the projection lens having a focal plane; and a light source unit which is arranged on a more rear side than a back side of the focal plane of the projection lens, wherein the projection lens is composed of two resin lenses (22, 24) which are arranged on the optical axis and include a first resin lens arranged more distant from the light source unit and a second resin lens arranged closer to the light source unit, wherein the first resin lens has a positive power, wherein the second resin lens has a lens face on a side opposite to the light source unit that is formed to be a face in which a change of a shape of the lens face is smaller than a change of a shape of a lens face in a side opposite to the light source unit on the first resin lens wherein the second resin lens has a wall thickness thinner than a wall thickness of the first resin lens, wherein the light source unit includes a light source and is configured so as to form a light source image that is emitted forward through the two resin lenses (22, 24) and forms a light distribution pattern including a boundary line between light and shade, substantially on the back side focal plane of the projection lens, characterized in that the second resin lens has a lens face having a positive power, and the second resin lens has a positive power, wherein the lens face having the positive power is arranged on a light source side, wherein a diffraction grating is provided on the lens face of the second resin lens on the side opposite to the light source unit, wherein the diffraction grating is formed to make the light of long wavelength out of the light emitted from the light source unit easier to be refracted than the light of short wavelength out of the light emitted from the light source unit to cancel chromatic aberration, which would otherwise occur if no diffraction grating were present, when the light is emitted from the light source unit and is emitted forward through a projection lens made of resin.