The present invention is made to provide a fixing structure for solid state image forming device made inexpensively and easily by simple caulking adhering method with keeping high positional accuracy, by which it is achieved that the solid state image forming device can be separated easily from the image focusing lens holding member when the image focusing lens holding member has a defect. In the fixing structure of present invention, an image focusing lens holding member 3 and an intermediate holding member 6 are adhered by caulking adhering method. Because one or more projecting portion 3c for painting adhesive material formed on the image focusing lens holding member 3, have smaller area than that of bottom surface 6a of the intermediate holding member 6, a space 10 is formed between the image focusing lens holding member 3 and the intermediate holding member 6, the solid state image forming device 1 fixed on the intermediate holding member 6 can be easily separated from the image focusing lens holding member 3 by inserting and turning a tool 11 whose width of top portion is smaller than the width of space 10.