A rigid polyurethane foam which has ultrafine cells, has a low thermal conductivity of 0.0190 W/(m·K) or lower, exhibits excellent heat insulating properties and flame retardancy, and has very little impact on global warming, without using a special apparatus such as a gas loading device. Provided is a rigid polyurethane foam which is obtained by mixing and reacting raw materials including a polyol, a polyisocyanate, a blowing agent, and a catalyst. The rigid polyurethane foam contains the polyol containing a polyester polyol having an aromatic component concentration of 17-35 wt. %, and a non-amine-based polyether polyol and/or an aromatic amine-based polyether polyol; the polyisocyanate in which MDI/TDI are mixed at a ratio of 4/6 to 9/1; and the blowing agent containing a halogenated olefin.