Method for producing molded article of fiber-reinforced plastic

A method for molding a fiber-resin mixture containing an inorganic reinforcing fiber and a thermosetting resin under heat and pressure, thereby producing a molded article of a fiber-reinforced plastic, comprising the steps of:

• measuring the elapsed time since a temperature of the thermosetting resin or the fiber-resin mixture reached a molding temperature at which a hardening reaction proceeds, measuring a loss angle δ of the thermosetting resin or the fiber-resin mixture in a dynamic viscoelasticity measurement, evaluating a relationship between the elapsed time and the loss angle δ, and calculating a range of the elapsed time, within which the loss angle δ is 0.55 to 1.57 rad after the loss angle δ reached a maximum value, as a pressurization start range based on the relationship;
• and
• heating the fiber-resin mixture to the molding temperature, and starting pressure application to the fiber-resin mixture while the elapsed time is within the pressurization start range.