To provide a highly versatile silencer for reducing a sound generated in a pipe for flowing fluid, when the type or use state of the pressure control device is different, and the pressure control device including the silencer and controlling pressure of the fluid in the pipe.

This silencer 10 comprises a plate-like part 50. The plate-like part 50 is arranged on the downstream side in a flow of the fluid more than a passing hole opened-closed by displacement of a piston 14 in the pipe for flowing the fluid. The plate-like part 50 is also arranged by partitioning an upstream side space and a downstream side space, and a plurality of through-holes 55 are formed. The through-holes 55 are formed to be blocked up, and can communicate the upstream space with the downstream space.