Since balcony remodeling was legalized, construction companies and residents are expanding their apartments before and after completion of a construction work. Enlarging living room by balcony remodeling could give some advantages such as increase of open space, while lots of problem are arisen in building environmental point. Researches on safety, dew condensation, energy effectiveness, lighting environment and thermal performance of exterior window have been proceeded, however researches in terms of acoustical problem were not dealt as much as the other building environmental elements. This study aims to compare the floor impact sound characteristics between apartments with and without balcony remodeling and to propose reasonable measurement method for floor impact sound in apartment based on experiment. Consequently, floor impact sound level was different when several methods are applied by setting up the measuring points in source room and receiving room differently, depending on the space whether living room is enlarged or not. Finally measurement method is proposed based on the results.