To prevent the occurrence of outgassing affecting a lens characteristic by covering a face touching a space where exposure energy passes by means of the coat of metal or a ceramic, which is formed by thermal spraying.

A lens-barrel 16 and a connection barrel 18 are manufactured by forming base materials by adjusting them to the forms, forming alumina base films on faces touching spaces 19a and 19b on the surfaces of the base materials and forming stainless metal coats 30 by plasma thermal spraying in cold thermal spraying from above the films. Since the meal coats 30 are formed by thermal spraying, contained impurity jumps out and is removed when thermal spraying materials become a high temperature and they are coated on the lens-barrel 16 and the connection barrel 18 in the state of high purity, outgassing from the metal coat 30 itself hardly occurs and outgassing from a base material side is interrupted. Since the coat is formed by cold thermal spraying, the base material is prevented from being heated to the high temperature and thermal distortion and the like are prevented from being added to the lens-barrel 16 and the connection barrel 18.