PURPOSE: To simple produce cross sipes different in shape and simply and easily produce block sipes having various functions by a method wherein a sipe forming member is produced by rabbet joining a board-like first member, which forms a sipe in one direction, to a board-like second member, which forms a sipe intersecting with the first member.

CONSTITUTION: In a first member 2, a rabbet 5 is formed on its tip 2a side from the tip edge to its base part 2b side. The width of the rabbet 5 corresponds to the board thickness of a second member 3. In the second member 3, a rabbet 6 is formed on its base part 3b side from the base end to its tip 3a side. The width of the rabbet 6 corresponds to the board thickness of the first member 2. A sipe forming member 1 is normally produced by imbedding the member 2 in a tire mold 4 and, after that, the member 3 is imbedded in the tire mold 4 in such a manner that the member 3 is rabbet joined to the member 2. However both the members 2 and 3, which have been joined to each other, may well be simultaneously imbedded in the tire mold 4. In the sipe 7 formed by means of the sipe forming member 1, two sipes 7A and 7B intersect each other at right angles. The ends of the respective sipes 7A and 7B can be made to be open from a block 8 to a groove between the blocks at both ends, blind at one end only, blind at both ends of each sipe or the like.