To obtain an optical element which makes it possible to obtain high shape accuracy by continuous processing and obviates the occurrence of cracking, chipping, etc., by determining the shape of non-optical function surfaces adjacent to optical functional surfaces by an interpolation equation which may be defined by using the coordinates at the ends of the optical functional surfaces and the value of tangent vectors.

The two optical functional surfaces 1 and 2 varying from each other are formed on one side of a substrate 32 of the optical element 31. The shape of the non-optical function surfaces is determined by using such interpolation function (for example, a tertiary Hermitian curve, etc.), which can be defined by using the coordinates at the ends of the optical functional lines on the surfaces obtained by cutting optical functional surfaces 1 and 2 of the press formed optical element 31 in the cutting progression direction (generator direction) of a cutting tool and the value of the tangent vectors. As a result, the connection of the plural optical functional surfaces by a smoothly curved surface free of discontinuous surfaces is made possible and the manufacture of the metal mold of an integral type by continuos processing is made possible. The optical element which makes it possible to obtain the high shape accuracy and obviates the occurrence of the cracking, chipping, the may be obtained.