PURPOSE: To achieve a finer diameter of an inserting part and a shorter axial length of a hard tip part by joining a protective glass out a photo detecting surface of a solid image sensor while a lens is fastened on the surface thereof as positioned the closest to an imaging side composing a group of objective lenses.

CONSTITUTION: A protective glass 13 comprising a balanced plane plate is fastened on a solid image sensor 12 by a means for adhesion on the like. A lens 4a is bonded on the surface of the protective glass 13 as positioned the closest to an imaging side composing a group of objective lenses 4. As the protective glass 13 is so arranged to be fastened direct on the solid image sensor 12 provided on a substrate 11 to leave no excess of space between members, the overall length can be reduced remarkably from the tip of a tube 5 to the substrate 11. This allows the shortening of the length of a hard tip part 1 comprising a tip part body 1a and a ring part 1b. Even in a three-layer junction structure, neither the lens 4a nor the protective glass 13 interferes with a wire 16. The solid image sensor 12 is smaller in outer diameter size than the lens 4a and the protective glass 13 has a size enough to cover a photo detecting surface 12a of the solid image sensor 12.