Provided is a pregrouted PC steel material comprising a PC steel stranded wire composed of a plurality of steel wires, a pregrout layer disposed on the outer periphery of the PC steel stranded wire so as to accommodate the PC steel stranded wire, a sheath covering the outer periphery of the pregrout layer, and a capsule including a pregrout-hardening agent and a film with which the agent is covered, the capsule being interposed among the steel wires constituting the PC steel stranded wire. The capsule has a strength such that the capsule is not broken before tensioning the PC steel stranded wire but is broken by a tensile force during the tensioning. Also provided is a method for hardening the pregrout layer.