Provided are a separator with improved oil separation efficiency, and a refrigeration cycle apparatus including the separator. The separator includes an inflow pipe portion, an oil storage portion, an oil return pipe portion, and an outflow pipe portion. The inflow pipe portion includes a swirling portion that defines a flow direction of refrigerant so as to swirl the refrigerant. The oil storage portion is connected to the inflow pipe portion. The oil return pipe portion is connected to a vertically lower side of the oil storage portion. The outflow pipe portion includes an opening end that faces the swirling portion. The outflow pipe portion extends from a region that faces the swirling portion to the outside of the oil storage portion. The opening end is configured such that the refrigerant discharged from the swirling portion can directly flow thereinto.