To provide a reinforcing frame material installing device of a truss structure capable of installing a reinforcing frame material in an optional place of a column without arranging a hole for inserting a bolt in the column.

This reinforcing frame material installing device is composed of the column 1 for constituting the truss structure for forming a dovetail groove-shaped recessed part 11 over the total length in the outer peripheral lengthwise direction, a pair of installing plates 3 for forming a fitting part 31 having a cross-sectional shape of bilaterally symmetrically dividing a cross- sectional shape of the recessed part, and the reinforcing frame material 2 sandwiched by the pair of installing plates, and fixed by a bolt and a nut, and is characterized in that when fixing the reinforcing frame material by the bolt and the nut by both installing plates by fitting the pair of installing plates to the recessed part of the column, the fitting part laterally expands, and is fixed in pressure contact and close contact to a wall surface of the recessed part.