To provide a sealing cap installed to an opening end of a cylindrical mechanical part without injuring the opening end and stably keeping the installation condition without slipping out even when rising of the internal pressure in the cylindrical mechanical part after installation.

The metal sealing cap 6 is installed to the opening end 2a of the cylindrical mechanical part 2 and closes an inner cylinder part 2b of the mechanical part 2. The sealing cap includes a disc-shaped cap body 7 and a cylindrical part 8 formed integrally and continuously at a peripheral edge part 7a of the cap body 7 and press-fitted into the inner cylinder part 2b of the mechanical part 2 from the opening end 2a of the cylindrical mechanical part 2. The cap body 7 includes a tapered shape part 7b reduced in diameter gradually toward the inside of the inner cylinder part 2b of the mechanical part 2.