To provide a semiconductor resin sealing device, with which the molding quality of resin sealing can be improved by having uniform thrust of a plurality of injection plungers and stabilized sliding property with an equal pressure injection plunger structure using a working fluid.

This resin sealing device in provided with an injection cylinder 2, having three working chambers 10 where three pistons 9 move slidingly and each working camber 10 on the side where a working fluid is airtightly sealed, injection plungers 1 which are connected to each piston 9 and injection pressure is applied to resin, a pressure sensor 3 which detects the pressure of the working fluid in the injection cylinder 2, a pressurizing means 12 which impart working pressure to the working fluid, and an arithmetic unit 8 which controls by feed-back the pressurizing force of the pressurizing means 12 through the detected pressure of the pressure sensor 3.