A piping system of a steam turbine plant includes: a piping member including a first pipe section including a first passage, a second pipe section including a second passage, a connection section arranged between the first pipe section and the second pipe section and including a connection passage that connects the first passage and the second passage, and a third pipe section including a third passage connected with the connection passage through an opening, the first pipe section being supplied with steam; a steam stop valve connected with the third pipe section; and a turbine bypass valve connected with the second pipe section. An angle made by a first central axis and a second central axis is larger than an angle made by the first central axis and a third central axis.
