A process of preparing clad contact material comprises forming a contact belt-like member by bonding an Au or Au alloy tape to the surface of an Ag or Ag alloy tape, thermally treating that contact member for forming an Au diffusion layer, and cladding that contact member having the Au diffusion layer to a base belt-like member made of Cu or a Cu alloy. Since, according to the process, the thermal diffusion treatment is carried out before the contact belt-like member is set in the base belt-like member, the thermal diffusion treatment of the contact belt-like member can be performed in the most suitable conditions for obtaining an Au diffusion layer with excellent characteristics, and no dissolution may occur at the interface between the two belt-like members.