A fluid controller (100) includes a piezoelectric pump (10), a valve (101), and a cuff (109). The valve (101) includes a first valve housing (191), a diaphragm (120), and a second valve housing (192). The second valve housing (192) has a second air hole (112), a third air hole (113), and a first valve seat (139). The second air hole (112) connects to the internal space of the cuff (109). The third air hole (113) connects to the outside of the fluid controller (100). The first valve seat (139) is formed around the third air hole (113). Together, the second valve housing (192) and the diaphragm (120) form a first flow passage (141). The first flow passage (141) connects the second air hole (112) and the third air hole (113) to each other. The second valve housing (192) has a protruded portion (140) that protrudes toward the diaphragm (120) and that forms a portion of the first flow passage (141). The shortest distance between the protruded portion (140) and the diaphragm (120) is less than the diameter (2r) of the third air hole (113).
