A fiber-reinforced plastic producing method capable of easily producing a fiber-reinforced plastic in which swelling and warpage are less likely to occur and of which excellent mechanical characteristics and isotropy are ensured, and a fiber-reinforced plastic in which swelling and warpage are suppressed from occurring. The fiber-reinforced plastic producing method has a step for obtaining a material (A) including a prepreg base material in which a region (B), where reinforcing fibers pulled and aligned in one direction are impregnated with a matrix resin and a plurality of cuts (b) are formed, and a region (C), where a plurality of cuts (c) are formed, are alternately formed in a direction orthogonal to a fiber axis of the reinforcing fiber, a step for hot-pressing the material (A) while moving the material (A) under specific conditions, and a step for cooling the pressed material (A) to obtain the fiber-reinforced plastic.