A flow passage forming member includes flow passage forming member main bodies 140 and 146 that are formed of a resin material and define at least a part of a flow passage, a metal protective film 200 that is provided on a surface of the flow passage forming member main body 140 and a surface of the flow passage forming member main body 146 defining at least the flow passage and is formed of a metal material, and a protective film 210 that is laminated on the metal protective film 200 and contains an oxide or a nitride of at least on element selected from the group consisting of tantalum (Ta), titanium (Ti), zirconium (Zr), niobium (bib), vanadium (V), hafnium (Hf), silicon (Si), aluminum (Al), tungsten (W), and yttrium (Y).

A flow passage forming member includes flow passage forming member main bodies 140 and 146 that are formed of a resin material and define at least a part of a flow passage, a metal protective film 200 that is provided on a surface of the flow passage forming member main body 140 and a surface of the flow passage forming member main body 146 defining at least the flow passage and is formed of a metal material, and a protective film 210 that is laminated on the metal protective film 200 and contains an oxide or a nitride of at least on element selected from the group consisting of tantalum (Ta), titanium (Ti), zirconium (Zr), niobium (Nb), vanadium (V), hafnium (Hf), silicon (Si), aluminum (Al), tungsten (W), and yttrium (Y).