SEALING STRUCTURE AND METHOD OF ASSEMBLING SEALING STRUCTURE

Provided are a sealing structure capable of providing consistent sealing performance for a prolonged time, and an assembling method of the sealing structure. An installation component 300 is provided with an annular fitting groove 310 in which a resin gasket 100 is mounted. The fitting groove 310 has a bottom with an annular projection 311 including a tapered surface 311a increasing in a diameter thereof from a pressure side (H) to a non-pressure side (L), and a tapered surface 311b decreasing in a diameter thereof from the pressure side (H) to the non-pressure side (L). The tip of the annular projection 311 is positioned closer to the pressure side (H) than a center in a width direction of the fitting groove 310.