In a threaded joint for steel pipes comprising a pin (1) and a box (2), each having a threaded portion (11 or 21), a sealing surface (13 or 23), and a shoulder surface (14, 15 or 24, 25), the sealing surface (13) of the pin (1) is formed by a tapered surface, and the sealing surface (23) of the box (2) is formed by a first curved surface portion with a large radius of curvature in the range of 15-120 mm, a tapered surface portion, and a second curved surface portion with a large radius of curvature again in the range of 15-120 mm.