Abstract: For device groups (3) each including devices (31) included in a processing plant (1) processing fluid and each having an occupied area (30) set therefor, connection information representing two specific device groups (3) are connected and paired via a pipe (4) and pipe information required for calculating use amount of a pipe material are set. Then, a first step, including arranging the device groups (3) in an installation area (10) of the processing plant (1) so that an outer edge of the occupied area (30) and a long side of a pipe-rack arrangement area (20) contact with each other, and a second step, including calculating a total use amount of the pipe material of the pipe (4) supported by a pipe rack (21, 22, 23), are repeated. From results obtained by changing the arrangement of the device groups (3), arrangements having small total use amounts of pipe materials are selected.