Mounting structure of a solid-state image pick-up device

A mounting structure includes a fixing plate to which an image pick-up device is fixed; screw holes formed on a supporting member; a first female threaded portion and a second female threaded portion having a smaller diameter than the first female threaded portion, formed in each screw hole; cylindrical adjustment members which are screwed into the screw holes, respectively, and are rotatable to adjust the axial position thereof; and set screws which are rotatably inserted through the fixing plate and respective axial holes of the cylindrical adjustment members to be engaged with the second female threaded portions of the screw holes to hold the fixing plate between each head portion of the set screws and each cylindrical adjustment member, respectively.