A process for producing a beam member formed by a reinforcing fiber base material which has a web portion and at least a pair of flange portions extending to both sides via at least a branching point from the web portion, at a cross-sectional surface orthogonal to a longitudinal direction of the beam member, and by a shaped filler which fills a gap having a wedge shape formed at the branching point, is provided. The shaped filler is produced by: (A) a filler supply process for supplying a filler member configured by reinforcing fibers; (B) a preshaping process for providing a preshaped filler having at least a wedge projection portion, by pressurizing the filler member by a preshaping mold; and (C) a filler deforming process for providing a shaped filler by deforming the preshaped filler.