Provided is a corrosion-resistant and wear-resistant member where a thermal-sprayed layer having corrosion resistance and wear resistance is formed on a surface of a metallic member which is brought into contact with a resin which generates a highly corrosive gas. Also provided is a thermal-spraying powder. The highly corrosion-resistant and wear-resistant member having a thermal-sprayed layer is one obtained by thermally spraying metallic powder on a metallic base material to form a thermal-sprayed layer on a surface of the metallic base material. The member is characterized in that the thermal-sprayed layer is a composite boride cermet of a tetragonal Mo2(Ni,Cr)B2-type or a tetragonal Mo2(Ni,Cr,V)B2-type. The powder for forming a thermal-sprayed layer is made of a composite boride cermet of a Mo2(Ni, Cr)B2-type and comprises 4.0 to 6.5 mass % of boron, 39.0 to 64.0 mass % of molybdenum, and 7.5 to 20.0 mass % of chromium, a balance being 5 mass % or more of nickel and unavoidable elements.