To provide a reinforcement fiber base material more excellent in formativeness than a conventional material, a preform of the reinforcement fiber composite material, and a reinforcement fiber composite material excellent in strength.

The reinforcement fiber base material 11 is formed of a laminate of a one-direction reinforcement fiber sheet 12 paralleling a reinforcement fiber in one direction and a fabric 13. The fabric 13 has a plurality of breaks 14 penetrating the direction of the thickness of the fabric 13. The plurality of the breaks 14 are arranged over an entire face of the fabric 13, and the generation of wrinkles of the fabric 13 is suppressed in forming by the plurality of the breaks 14.