PURPOSE: To provide the method capable of easily and efficiently preparing the block plan which an electric equipment is arranged at a prescribed position.

CONSTITUTION: In this method, the block plan in which the electric equipment is arranged at the prescribed position of a room is prepared. The preliminarily decided attachment rule of the electric equipment is held as a database. On the other hand, the area and constitution of the room is read from the data of a room equipment plan recorded in a recording medium, the arrangement of the electric equipment at the appropriate position according to the room is decided from the read information and the database, and the mark of the electric equipment is plotted on the room equipment plan, thereby the block plan of the electric equipment is prepared.