The integrated Modular water Reactor (IMR), which is one of small sized water reactors, has Steam Generators in Liquid (SGL) area and in Vapor (SGV) area of the Reactor Vessel (RV) respectively. SGL is a heat exchanger that generates steam by the heat transfer from the primary coolant water and SGV generates steam from primary coolant vapor. We study basic designs of SGL and SGV from the view points of heat transfer performance, reliability of SGs, manufacturability and SG arrangement in the RV. As a result, a vertical type U-tube SG is selected for SGL, because of lower pressure drop and manufacturability by proven technology for current PWR SGs. On the other hand, a horizontal type C-tube SG is selected for SGV, mainly because of the heat transfer performance and the advantage for arrangement in the RV.