A gas-liquid separator comprising: a housing being supplied with water-containing gas; a gas-liquid separation portion being provided inside the housing and separating water from water-containing gas; a water storage portion being arranged on a bottom portion of the housing and storing water separated by the gas-liquid separation portion; a valve mechanism enabling discharge of and stop of the discharge of water in the water storage portion via a discharge flow path communicating with the water storage portion, wherein an inner wall of the housing has a guide surface flowing water toward the water storage portion and is provided with a regulating portion regulating staying of water in a vicinity of a flow-in port of the discharge flow path; and a filter removing dust contained in water flowing into the water storage portion; wherein, the regulating portion is arranged in a region extending along an outer periphery of the filter, the regulating portion is provided with a plurality of regulating flow paths inhibiting water droplets of a predetermined amount flowing in from the guide surface from flowing, and allowing a greater amount of water than the water droplets of a predetermined amount to flow, the regulating portion has a vertical wall-shaped portion surrounding an outer periphery of an opening of the water storage portion, and the regulating flow paths are formed by a plurality of recess-shaped portions formed on an upper edge portion of the vertical wall-shaped portion. a housing being supplied with water-containing gas; a gas-liquid separation portion being provided inside the housing and separating water from water-containing gas; a water storage portion being arranged on a bottom portion of the housing and storing water separated by the gas-liquid separation portion; a valve mechanism enabling discharge of and stop of the discharge of water in the water storage portion via a discharge flow path communicating with the water storage portion, wherein an inner wall of the housing has a guide surface flowing water toward the water storage portion and is provided with a regulating portion regulating staying of water in a vicinity of a flow-in port of the discharge flow path; and a filter removing dust contained in water flowing into the water storage portion; wherein, the regulating portion is arranged in a region extending along an outer periphery of the filter, the regulating portion is provided with a plurality of regulating flow paths inhibiting water droplets of a predetermined amount flowing in from the guide surface from flowing, and allowing a greater amount of water than the water droplets of a predetermined amount to flow, the regulating portion has a vertical wall-shaped portion surrounding an outer periphery of an opening of the water storage portion, and the regulating flow paths are formed by a plurality of recess-shaped portions formed on an upper edge portion of the vertical wall-shaped portion. wherein, the regulating portion is arranged in a region extending along an outer periphery of the filter, the regulating portion is provided with a plurality of regulating flow paths inhibiting water droplets of a predetermined amount flowing in from the guide surface from flowing, and allowing a greater amount of water than the water droplets of a predetermined amount to flow, the regulating portion has a vertical wall-shaped portion surrounding an outer periphery of an opening of the water storage portion, and the regulating flow paths are formed by a plurality of recess-shaped portions formed on an upper edge portion of the vertical wall-shaped portion.