A gasoline fuel supply system includes a feed pump part, an inline pump part, and a high-pressure pump part. The feed pump part includes a non-positive displacement electric pump, and pumps a gasoline fuel from a fuel tank and discharges at a feed pressure. The inline pump part includes a non-positive displacement mechanical pump, and pressurizes the gasoline fuel discharged from the feed pump part and discharges at a middle pressure. The high-pressure pump part includes a positive displacement mechanical pump, and pressurizes the gasoline fuel discharged from the inline pump part and discharges at a supply pressure to a fuel injection valve.