Disclosed is a seam welded tinplate can having a side seam formed by welding, wherein the inner and outer surface portions of said side seam comprise an outermost layer formed of an oxide, which has a thickness of 50 to 400 A, and an intermediate layer formed mainly of an iron-tin alloy layer, which has a thickness corresponding to 5 to 100% of the thickness of the total tin layer, and a resin or resin composition containing a polar group selected from the group consisting of carbonyl, hydroxyl, ether and epoxy groups at a concentration of 10 to 2000 millimoles per 100 g of the resin is coated on at least one of said inner and outer surface portions of said side seam.