The composition of different types of architectural and urban spaces with a courtyard can be identified and explained by what we call the "principle of association of MA(Japanese meaning a room space)" based on two neccessary conditions : an opening for light and air of the MA and an efficient utilization of the site. 1) Different plans of houses with a courtyard result from the principle applied to the sites of various forms. 2) The principle permits to assimilate the galeries to the architecture with a courtyard. 3) The housing estates composed around a courtyard on large sites are a planning choice rather than the necessity of the principle. 4) A block of houses with a courtyard can be reorganized by the rearrangement according to this principle.
