There is provided a co-injection-molded multilayer structure having a barrier layer and outer layers laminated on both sides of the barrier layer, wherein the barrier layer is made of a resin composition comprising an ethylene-vinyl alcohol copolymer (A) and an alkali metal salt (B) of a higher fatty acid having a melting point of 250° C. or lower; a content of the alkali metal salt (B) in the barrier layer is 50 to 1500 ppm in terms of metal atoms; and the outer layers are made of a resin composition comprising an unmodified polypropylene (E) and a maleic anhydride-modified polypropylene (F) having a lower melt viscosity than that of the unmodified polypropylene (E). Although it has no adhesive layers, the co-injection-molded multilayer structure exhibits excellent adhesiveness between the barrier layer made of an EVOH resin composition and the outer layer made of a polypropylene resin composition.