A threaded joint for steel pipes comprising: a pin including an externally threaded portion, a nose extending from the externally threaded portion toward an end of a pipe, and a shoulder portion disposed at a distal end of the nose; and a box including an internally threaded portion that forms a threaded portion by being threadedly connected with the externally threaded portion, an inner peripheral face that faces an outer peripheral face of the nose of the pin, a nose of the box that faces an outer peripheral face of the nose and a shoulder portion that is in contact with the shoulder portion of the pin, wherein, when the pin and box are threadedly connected with each other and the outer peripheral face of the nose of the pin and the inner peripheral face of the nose of the box come into metal-to-metal contact with each other at a contact portion, the contact portion serves as a seal portion, wherein the threaded portion has a negative load flank angle, the shoulder portion (12, 14) has a negative torque shoulder angle, and the ratio L/d 0 of a length L of the nose and a pipe outside diameter d 0 is equal to or higher than 0.08, and wherein the torque shoulder angle of the shoulder portion of the pin and the torque shoulder angle of the shoulder portion of the box are smaller than -15°, wherein a strain ε of the seal portion in a pipe circumferential direction, which is calculated as ε = δ/D ∗ 100 (%), is equal to or larger than 0.30%, where D is a seal diameter that is defined as an outside diameter of the pin at a seal point that is a point on the outer peripheral face of the nose of the pin at which the outer peripheral face first comes into contact with the inner peripheral face of the nose of the box and δ is an amount of interference that is defined as an amount by which the outside diameter at the seal point is reduced by the box when the pin and the box are threadedly connected with each other. a pin including an externally threaded portion, a nose extending from the externally threaded portion toward an end of a pipe, and a shoulder portion disposed at a distal end of the nose; and a box including an internally threaded portion that forms a threaded portion by being threadedly connected with the externally threaded portion, an inner peripheral face that faces an outer peripheral face of the nose of the pin, a nose of the box that faces an outer peripheral face of the nose and a shoulder portion that is in contact with the shoulder portion of the pin, wherein, when the pin and box are threadedly connected with each other and the outer peripheral face of the nose of the pin and the inner peripheral face of the nose of the box come into metal-to-metal contact with each other at a contact portion, the contact portion serves as a seal portion, wherein the threaded portion has a negative load flank angle, the shoulder portion (12, 14) has a negative torque shoulder angle, and the ratio L/d 0 of a length L of the nose and a pipe outside diameter d 0 is equal to or higher than 0.08, and wherein the torque shoulder angle of the shoulder portion of the pin and the torque shoulder angle of the shoulder portion of the box are smaller than -15°, wherein a strain ε of the seal portion in a pipe circumferential direction, which is calculated as ε = δ/D ∗ 100 (%), is equal to or larger than 0.30%, where D is a seal diameter that is defined as an outside diameter of the pin at a seal point that is a point on the outer peripheral face of the nose of the pin at which the outer peripheral face first comes into contact with the inner peripheral face of the nose of the box and δ is an amount of interference that is defined as an amount by which the outside diameter at the seal point is reduced by the box when the pin and the box are threadedly connected with each other.