To facilitate transport by reducing weight of a pressure gauge inspection unit, and shorten inspection time.

Pieces of H-shaped piping 9, 9a and 13 are arranged on a base 8, and a reference pressure gauge 10 is installed. A nitrogen cylinder is installed in cylinder installing piping 12, and gas is introduced. A pressure gauge to be inspected is installed in pressure gauge installing piping 16, and a pressure reducing valve is adjusted, and an indication value of the reference pressure gauge 10 at respective inspection pressure time and an indication value of the pressure gauge are compared with each other. An inspection can be performed without using a weight or without using oil as compared with a conventional reference plumb bob type inspection unit.