Two kinds of Fe-16%Cr-30%Mo-(C,B,P) alloy powders having high ability to form an amorphous phase were thermal sprayed onto mild steel substrate using HVOF and APS processes. Perfectly amorphous coating was formed not only by the HVOF process but also by the APS process. The passive current densities of the amorphous coatings sprayed by the HVOF and APS processes were close each other and significantly low compared with that of SUS316L coating in 1 mol·L⁻¹ HCl solution. The coatings of perfectly amorphous phase were little corroded after immersion tests in 1 mol·L⁻¹ HCl solution for one week, though the coatings composed of the mixture of amorphous and crystalline phases corroded markedly.