Friction-type high-strength bolted joints are widely used in the repair and strengthening of steel bridges. Slip resistance tests were conducted on joints with one side of this joint using an etched primer steel plate treated by power tool as existing member, and the other side with coating of inorganic zinc rich paint as a factory-made member. As a result, the slip coefficient was stable when the thickness of the inorganic zinc coating was 100 μm or greater under the conditions used in this test. As application conditions for obtaining a slip coefficient of 0.4, we propose that the degree of surface treatment with a power tool be such that the remaining coating film cannot be visually confirmed, and that the thickness of the inorganic zinc coating be in the range of 100 to 200 μm.