A double row tapered roller bearing comprising: an outer ring serving as a bearing ring having an annular shape; an inner ring disposed on an inner circumferential side of the outer ring and serving as a bearing ring having an annular shape, the inner ring having an outer circumferential surface facing the outer ring and having two rows of grooves having a bottom surface serving as a raceway surface ; and tapered rollers disposed in the grooves in contact with the raceway surface of the inner ring and being also in contact with the outer ring , at the outer circumferential surface of the inner ring , a region adjacent to the groove including a hardened region extending from an inner peripheral surface of the groove to the region adjacent to the groove , and an unhardened region located at a position farther from the groove than the hardened region and being smaller in hardness than the hardened region , the inner ring being constituted of steel containing at least 0.43 mass % and not more than 0.65 mass % of carbon, at least 0.15 mass % and not more than 0.35 mass % of silicon, at least 0.60 mass % and not more than 1.10 mass % of manganese, at least 0.30 mass % and not more than 1.20 mass % of chromium, and at least 0.15 mass % and not more than 0.75 mass % of molybdenum with the rest consisting of iron and an impurity, wherein an angle that the raceway surface forms with a central axis of the inner ring is 40° or more and 50° or less; characterized in that in outer circumferential surface, a distance from an end of the opening of groove to an end of hardened region is set to 2 mm or more and 10 mm or less. an outer ring serving as a bearing ring having an annular shape; an inner ring disposed on an inner circumferential side of the outer ring and serving as a bearing ring having an annular shape, the inner ring having an outer circumferential surface facing the outer ring and having two rows of grooves having a bottom surface serving as a raceway surface ; and tapered rollers disposed in the grooves in contact with the raceway surface of the inner ring and being also in contact with the outer ring , at the outer circumferential surface of the inner ring , a region adjacent to the groove including a hardened region extending from an inner peripheral surface of the groove to the region adjacent to the groove , and an unhardened region located at a position farther from the groove than the hardened region and being smaller in hardness than the hardened region , the inner ring being constituted of steel containing at least 0.43 mass % and not more than 0.65 mass % of carbon, at least 0.15 mass % and not more than 0.35 mass % of silicon, at least 0.60 mass % and not more than 1.10 mass % of manganese, at least 0.30 mass % and not more than 1.20 mass % of chromium, and at least 0.15 mass % and not more than 0.75 mass % of molybdenum with the rest consisting of iron and an impurity, wherein an angle that the raceway surface forms with a central axis of the inner ring is 40° or more and 50° or less; characterized in that in outer circumferential surface, a distance from an end of the opening of groove to an end of hardened region is set to 2 mm or more and 10 mm or less. <EOS>