An outer surface 21a of a distal-end cover 21 and a bonding surface 24a of a bonding end portion 24 of the distal-end cover 21 and a bonding surface 25a of a bonding end portion 25 of a drum portion cover are subjected to plasma treatment, e.g., atmospheric plasma treatment. Plural minute uneven portions are formed on the outer surface 21a and the bonding surfaces 24a and 25a, whereby hydrophilicity of the outer surface 21a and the bonding surfaces 24a and 25a is improved. The bonding surfaces 24a and 25a are engaged and bonded with each other by an adhesive agent. The liquid-tightness of a container is secured, while safety and translucency of the container are further improved.
