The maps in the world of the role playing games provide not only areas for motions and actions of player characters, but also worlds of totally included monsters and NPC(Non Player Character). However, the design of maps and monsters in them could not be tested for their balances until the games had been developed quite a bit. So they need additional expense of extension period of developments. In this paper, we have designed and developed a map simulator to expect the popularities of the maps in the early stage of the game planning in order to prevent inefficient concentration of users on some maps by expecting the popularities of the maps in the early stage of game planning and by setting the parameters of monster arrangements in the map.