A flow apparatus comprising a bypass part that is a member having a shape of a plate, and a pair of external connection parts that is a pair of members having a shape of a plate and being laminated on two principal surfaces of said bypass part, respectively, wherein:
- said bypass part comprises one first member that is a member having a shape of a sheet, in which a first inlet hole that is at least one through-hole having a predetermined size and a predetermined shape, a first outlet hole that is at least one through-hole having a predetermined size and a predetermined shape, and at least one groove in communication with said first inlet hole and said first outlet hole are formed, or said bypass part comprises two or more said first members laminated such that said first inlet holes of said first members adjacent to each other airtightly communicate with each other and said first outlet holes of said first members adjacent to each other airtightly communicate with each other,
- a second inlet hole that is at least one through-hole having a predetermined size and a predetermined shape is formed in either of said pair of said external connection parts, and a second outlet hole that is at least one through-hole having a predetermined size and a predetermined shape is formed in either of said pair of said external connection parts,
- said first inlet hole formed in said first member and said second inlet hole formed in said external connection part are configured to airtightly communicate with each other, and said first outlet hole formed in said first member and said second outlet hole formed in said external connection part are configured to airtightly communicate with each other
- said first member is constituted as a laminated object in which a second member that is one member having a shape of a sheet and a third member that is one member having a shape of a sheet are laminated,
- a third inlet hole that is at least one through-hole having a predetermined size and a predetermined shape, a third outlet hole which is at least one through-hole which has a predetermined size and a predetermined shape, and a slit that is at least one through-hole having a predetermined width and a predetermined length are formed in said second member,
- a fourth inlet hole that is at least one through-hole having a predetermined size and a predetermined shape and a fourth outlet hole which is at least one through-hole which has a predetermined size and a predetermined shape are formed in said third member,
- said third inlet hole of said second member and said fourth inlet hole of said third member airtightly communicate with each other to form said first inlet hole in said first member, and said third outlet hole of said second member and said fourth outlet hole of said third member airtightly communicate with each other to form said first outlet hole in said first member,
- an inlet end that is an end closer to said third inlet hole among both ends of said slit and said third inlet hole are configured to airtightly communicate with each other through said fourth inlet hole, and an outlet end that is an end closer to said third outlet hole among both ends of said slit and said third outlet hole are configured to airtightly communicate with each other through said fourth outlet hole, and
- an aperture plane other than said inlet end and said outlet end of said slit formed in said second member is airtightly closed with a portion of said third member where said fourth inlet hole and said fourth outlet hole are not formed to form said groove in said first member.