Abstract: A flexible pattern for forming casting molds can be withdrawn from the mold, without need of partitioning and reassembling, and includes a pattern member made by coupling a plurality of outer plates, having a configuration corresponding to a desired predesigned casting, by means of joint members, which are freely removable, and an airtight bag installed in the inner periphery of the pattern member. The pattern member and the airtight bag are united in a single body.