A method for manufacturing a prepreg in which a reinforcing substrate is impregnated with a thermosetting matrix resin. In the method, the reinforcing substrate is moved in a traveling direction. The thermosetting matrix resin is supplied to an outer circumferential surface of a transferring roller. The thermosetting matrix resin which substantially contains no solvent and which is in. a molten state is transferred from the outer circumferential surface of the transferring roller to a first surface of a reinforcing substrate while the reinforcing substrate moves. The thermosetting matrix resin which is transferred to the first surface is forced to permeate through the reinforcing substrate by pressing at least one pressing roller on the thermosetting matrix resin transferred to the first surface while the reinforcing substrate moves. The reinforcing substrate impregnated with the thermosetting matrix resin is heated to semi-cure the thermosetting matrix resin.