In an alloy coating film having a diffusion barrier layer and an aluminum reservoir layer on a substrate, the diffusion barrier layer is composed of a single phase that is a Re—Cr—Ni—Al system σ phase containing Al by less than 1 atomic %, or composed of a first phase which is the Re—Cr—Ni—Al system σ phase and one or more second phases selected from a γ phase, γ′ phase and β phase.