An object of this invention is to provide a parboiled rice manufacturing apparatus capable of efficiently manufacturing good-quality parboiled rice without increasing the overall size of the apparatus. A parboiled rice manufacturing apparatus according to this invention includes a drum which has a raw material hatch provided at a peripheral surface and is disposed to be rotatable about a horizontal axis, a heating unit which is disposed inside the drum and heats an interior of the drum, an agitation unit which is disposed inside the drum and agitates a raw material charged through the raw material hatch into the drum, a steam supply unit which supplies steam into the drum, a pressure adjustment unit which has a valve allowing communication of the interior of the drum with outside air and allows increase of pressure inside the drum with steam supplied from the steam supply unit by closing the valve at the time of processing of the raw material through the pressurized steam-boiling treatment, a water addition
