To provide a high-performance accumulator that makes a thick outlet pipe applicable to a compact container and can reduce pressure loss while reducing material and processing costs.

An accumulator includes: a cylindrical body 1 with a cylindrical shape; an upper mirror plate 2 closing an upper part 1A and a lower mirror plate 3 closing a lower part 1B; and an inlet pipe 4 and an outlet pipe 5; wherein the outlet pipe 5 has a double-pipe structure of a large-diameter outer pipe 6 and a small-diameter inner pipe 7 inside the cylindrical body 1. An upper part 6A of the outer pipe 6 is open to the inside of the cylindrical body 1 and a lower part 7B of the inner pipe 7 is open to the inside of the outer pipe 6. The inner pipe 7 is fixed to the upper mirror plate 2 in a through state, and the outer pipe 6 is fixed to a bottom part 3B of the lower mirror plate 3. An oil return hole 8 is provided to the outer pipe 6.