PURPOSE: To mold a multi-layer parison whose interlaminar adhesion properties are favorable, by a method wherein an inner and outer surface layers and a core ingredient are formed respectively by one side and the other side ingredients to be injected within a cavity for molding the same parison.

CONSTITUTION: A cavity mold 1, neck mold 2 and core 3 are clamped and a cavity 4 which is in the same shape as a multi-layer parison P is formed. When first molten resin 5 is injected into the cavity 4 by an injection device 7 through a directional control valve 6, a part of the cavity 4 which has brought into contact with said wall surface and meets with film resistance by the wall surface hardly moves. Then if the inside of the cavity 4 is filled with the molten resin through control of specified quantities of the first and second molten resin when the second molten resin 8 is injected by the injection device, the multi-layer parison P whose materials of the inner and outer surface layer 10 and core 11 are different from each other can be formed.