In a tread part, a land part (block) partitioned by a main transverse groove is provided with a thin groove having a narrower groove width than the main transverse groove and extending in a tire width direction. On a groove lateral face which is one of opposing groove lateral faces of the thin groove, ridges projecting toward the other groove lateral face and extending in a depth direction of the thin groove are provided. A plural number of the ridges are provided in parallel to each other at intervals in a length direction of the thin groove, and an extending length in the depth direction is set up to include at least two kinds.