PURPOSE: To improve the production efficiency of a container for medical treatment by sealing multilayer sheets of which the innermost layer is formed of a nylon material and the other layers consist of a material contg. a polymer blend composed of a block copolymer of a styrene, etc., and specific components, such as butadiene and resins, such as polyethylene, by high-frequency induction heating, thereby forming the container.

CONSTITUTION: The innermost layer is formed of the nylon material. The block copolymer is formed of the part consisting essentially of at least one kind selected from a group consisting of styrene and a group consisting of ethylene and butadiene and isoprene and its hydrogen additive. The multilayer sheets are formed by using the material contg. the polymer blend composed of the copolymer and the resin consisting essentially of at least one kind selected from the group of the polyethylene, polypropylene and polybutene as the material for the other materials. The multilayer sheets are sealed 3 to each other or the multilayer sheets and the parts contg. the nylon material are sealed to each other by a high-frequency electrical heating method, by which the container is formed.