A multistage pressure condenser includes, a high pressure chamber and a low pressure chamber, a pressure partition wall which partitions an inner portion of the low pressure chamber to an upper portion and a lower portion, a cooling pipe group which condenses low pressure side steam to low pressure side condensate, a reheat chamber positioned in the lower portion of the low pressure chamber and in which the low pressure side condensate which flows down through the porous plate is stored, high pressure side steam introduction portion for introducing high pressure side steam in the high pressure chamber to the reheat chamber, liquid-film forming portion which guides the low pressure side condensate which flows down through the porous plate to the reheat chamber while dispersing the low pressure side condensate on a surface, and air feeder for promoting the flow of the high pressure side steam.