PURPOSE: To provide a mold for forming a tile which makes grooves on the rear of a tile simply into a dovetail groove structure.

CONSTITUTION: A mold 1 for forming a tile has the following requirements. A molding face 1f for forming the rear face of a tile is formed of a high strength elastic product 1h such as urethane rubber. In addition, projecting strips 3a to 3c for forming grooves in the rear face of the file are formed on the elastic product 1h. If the projecting strips 3a to 3c are formed to be across the center of the molding face 1f, the angles α1, α1 of the upper two corners or one of these corners are made acute. In addition, if the projecting strips are formed to be deviated from the center of the molding face 1f, the angle α2 of the upper corner to the outer side from the center as a reference is made acute nd at the same time, the angle α3 of said corner to the inner side is set at about 90°C or higher.