To provide a cold-worked steel product with which even in the case of giving a load exceeding elastic range during use, the development of brittle fracture can be avoided.

In the cold-worked steel product which receives the large plastic strain exceeding the elastic limit in this cold-worked part during use by supplying while holding the worked strain at the cold-working time in the product shape, this cold-worked steel product excellent in the brittle fracture resistant characteristic is characterized in that a plurality of strain localizing grooves having ≥ 0.01 mm depth and ≥ 1 mm length are arranged for preventing the brittle fracture on the surface of the cold-worked part.