A torque sensor of the type utilizing magnetostriction of either a shaft made of a magnetostrictive magnetic alloy, or a magnetostrictive magnetic alloy layer formed on an outer peripheral surface of a shaft is disclosed, in which coils are disposed around the shaft for detecting a magnetic property of the magnetostrictive magnetic alloy, a tubular magnetic yoke made of a magnetic alloy having a soft magnetic property and disposed around the coils for excluding the influence of a disturbance magnetic field and completing a closed magnetic circuit, and a hollow cylindrical container disposed around the magnetic yoke. The torque sensor thus constructed has a high measuring accuracy and an excellent thermal stability.