A frame structure of a loom includes a frame formed by connecting a pair of side frames, to each of which a beam support for supporting a warp beam is fixed, by a plurality of beam materials, and one or more pair of height position setting members arranged between a loom installation surface and each of the side frames. Each of the height position setting members is fixed to the installation surface and the corresponding side frame. The pair of height position setting members are provided as a support structure configured such that a fixed position with respect to the corresponding side frame on at least one of a let-off side and a take-up side is an inner surface or an outer surface of the side frame.