A method of manufacturing a metal frame of an image forming apparatus includes assembling a first support, a second support, and a connecting member using a first jig having a base portion, whereafter there is a positioning of a position where the first support, the second support, and the connecting portion are fixed using a second jig having an insertion portion. In the first support, the insertion portion is inserted into a hole portion formed in a second metal plate so that the second metal plate moves upward in the vertical direction with respect to a first metal plate, and a restricting portion formed on one of the first and second metal plates abutted to the other metal plate in the assembly are separated from each other. The first support and the connecting member are fixed to each other, and the second support and the connecting member are fixed to each other.