To prevent a molding face side from becoming rusty and at the same time, minimize surface contamination to mitigate an after-treatment by forming a coating layer of a transparent rust-inhibitive coating on the molding face side of a steel-made concrete form body.

A coating layer 2 of a transparent rust-inhibitive coating is formed on the molding face 1A side of a form body 1 of a steel-made concrete form. In this case, a highly heat-resistant lacquer coating is used which is quick- drying and easily applicable as a rust-inhibitive coating and allows wet on wet coat application, contributing to the formation of a hard and durable coat. This lacquer coating is applied a plurality of times to obtain the coating layer 2. In addition, a parting compound such as a dimethyl silicone oil is applied to the surface of the coating layer 2 according to necessity. Thus it is possible to inhibit rust to be generated on the molding face 1A side of the concrete form and at the same time, prevent an extraneous coating on the surface of a manufactured concrete product from becoming conspicuous and further, mitigate an after-treatment.