PURPOSE: To provide an attachment device of a solid-state image pickup element which can easily and satisfactorily decide the position of the image pickup element by preventing the deterioration of adhesive power of an adhesive that is caused. by the heat generated when the fused metals are jointed together.

CONSTITUTION: An attachment device of an image pickup element 3 consists of a spectroscopic prism 1, the element 3, and the 1st and 2nd attachment metallic parts 2 and 4 which decide the positions of the prism 1 and the element 3 respectively. The plate thickness is partly reduced at a fused metal joint part 5 between both parts 2 and 4 so that the heat capacity is reduced and the inflow of heat is suppressed to the adhesion parts 6 and 7. Thus it is possible to prevent the deterioration of adhesive power between the prism 1 and the parts 2 and also between the element 3 and the parts 4.