A cylindrical roller bearing includes an inner ring having a flange portion provided with a roller guide-surface which guides the end faces 4a of the cylindrical rollers having diameter of Da. The end face 4a away from a center axis of the cylindrical roller by 0.40 Da in the radial direction is a first position A, and the end face 4a away from the center axis by 0.35 Da is a second position B, the end face 4a contacts with the roller guide-surface between the first and second positions A and B, the end face 4a has a convex-shaped crowning portion 4b having a continuous curve which passes the first and second positions A and B, and an angle .alpha. formed between a line connecting the first and second positions A and B and a line perpendicular to the center axis is set to be 0.5.degree. or less.