PURPOSE: To scan the surface to be examined of a wide range at good image forming performace with a compact constitution by employing 2-face 1 group image forming lens for the scanning lens to be disposed between a deflector and the surface to be scanned and forming part of the respective faces to reflecting faces and the remaining portions to transmission faces.

CONSTITUTION: The image forming lens 1 for scanning used in the scanning optical system of a laser beam scanning recorder, etc. has a Y1 face and Y2 face. The Y1 face is bisected to a transmission region 2 of luminous flux and reflection region 3. Likewise, the Y2 face is also bisected to a transmission region 5 and reflection region 4. The transmission region 2 of the Y1 face and the reflection region 4 of the Y2 face as well as the reflection region 3 of the Y1 face and the transmission region 5 of the Y2 face are opposedly provided. Incident light I0 enters the transmission region 2 of the Y1 face where it refracts and transmits, thence it reflects on the reflection region 4 of the Y2 face. And it again reflects on the reflection region 3 of the Y1 face and refracts and transmits through the transmission region 5 of the Y2 faces. In this way, it reflects twice in the inside, thus the radius of curvature becomes large and the correction of coma aberration and astigmatism becomes advantageous.