A method for manufacturing an insulating film laminated structure includes a step of forming a first high-k film on a semiconductor substrate, a step of processing the semiconductor substrate in a processing chamber of a plasma processing apparatus by using a plasma to form an oxide film on an interface between the semiconductor substrate and the first high-k film, and a step of forming a second high-k film on the first high-k film. A plasma oxidation process is performed by using a plasma of an oxygen-containing gas at a processing temperature of the semiconductor substrate in a range from 20° C. to 145° C. while setting a power density of a total power of microwaves to be within a range from 0.035 kW/m2 to 3.5 kW/m2 with respect to a total area of a conductive member facing an inner space of the processing chamber and microwave transmitting windows.