To improve the dissolving efficiency of a vapor component without deteriorating the water resistance and pressure resistance of a hydrophobic membrane.

This membrane module is composed of a hydrophobic hallow yarn membrane 1 having an outer surface lowered in the contact angle to the a liquid by surface modifying with plasma treatment, ultraviolet irradiation or the like. Plural numbers of the surface modified hydrophobia hallow yarn membrane 1 are bundled to be housed in a housing 2 and both end parts of the hollow yarn membrane 1 are sealed and fixed to both opening ends of the housing 2 with a resin 3. The liquid 6 is supplied from a liquid inlet 4 of the housing 2, passed through the outside of the hollow yarn membrane 1 and discharged from a liquid outlet 5. The vapor 7 is supplied from one end part of the housing 2, passed through the inside of the hollow yarn membrane 1 and discharged from another end part of the housing 2. Since the outer surface of the hollow yarn membrane 1 is made excellent in wettability, the surface area of liquid wetting part is enlarged and the dissolving rate of the vapor component passed though the hollow yarn membrane 1 is increased.