Abstract: A substrate, a diaphragm, and a piezoelectric actuator are laminated in this order in a first direction, the diaphragm includes a first layer containing silicon as a constituent element, a second layer disposed between the first layer and the piezoelectric actuator, and containing any one or both of at least one metal element selected from the group made of chromium, titanium, aluminum, tantalum, hafnium, and iridium, and silicon nitride, as a constituent element, and a third layer disposed between the second layer and the piezoelectric actuator and containing zirconium as a constituent element, and a fourth layer containing any one or both of at least one metal element selected from the group made of chromium, titanium, aluminum, tantalum, hafnium, and iridium, and silicon nitride, as a constituent element is provided on the third layer on a piezoelectric actuator side.

Abstract: A fixed scroll member includes a fixed base and a spiral fixed tooth member mounted to the fixed base. An orbiting scroll member is made of a resin material and includes an orbiting base arranged to face the fixed base; and a spiral orbiting tooth member. A housing is configured to house the fixed scroll member and the orbiting scroll member with the fixed scroll member being fixed thereto. An orbiting slide surface is located to be radially outside of the orbiting base of the orbiting scroll member, and a housing slide surface is formed on a portion of the housing. The portion is made of a metal material and is arranged to face the orbiting slide surface. The orbiting slide surface is in slidable contact with the housing slide surface. The portion of the housing has an outer wall exposed to atmospheric air.