A torque detector comprising: a permanent magnet; a magnetic yoke (14A, 14B) disposed within a magnetic field formed by the permanent magnet, the magnetic yoke (14A, 14B) configured such that a position of the magnetic yoke (14A, 14B) relative to the permanent magnet varies; a magnetic convergence unit having a cylindrical shape, the magnetic convergence unit including a magnetic convergence ring holder (20A, 20B) having a cylindrical shape so as to surround the magnetic yoke (14A, 14B), a magnetic convergence ring (19A, 19B) attached to an inner peripheral surface of the magnetic convergence ring holder (20A, 20B) to collect a magnetic flux of the magnetic yoke (14A, 14B), and a magnetic shield fitted and attached onto an outer peripheral surface of the magnetic convergence ring holder (20A, 20B); and a magnetic sensor configured to detect a magnetic flux of a magnetic circuit formed by the permanent magnet, the magnetic yoke (14A, 14B), and the magnetic convergence ring (19A, 19B), wherein the outer peripheral surface of the magnetic convergence ring holder (20A, 20B) has an insertion portion (50, 51; 61) into which the magnetic shield is inserted when the magnetic shield is fitted onto the magnetic convergence ring holder (20A, 20B), and the magnetic shield has an inserting portion to be inserted into the insertion portion (50, 51; 61) of the magnetic convergence ring holder (20A, 20B) in an insertion direction, the inserting portion of the magnetic shield having an engaging member (41a, 41b; 43) that is always engaged with an inner surface of the insertion portion (50, 51; 61) of the magnetic convergence ring holder (20A, 20B) to restrict movement of the inserting portion of the magnetic shield in a counter-insertion direction during its insertion in the insertion portion (50, 51; 61) of the magnetic convergence ring holder (20A, 20B); characterized in that the insertion portion (50, 51; 61) of the magnetic convergence ring holder (20A, 20B) has a first inner surface (52, 53; 62a) and a second inner surface (54, 55) configured to restrict relative movement between the engaging member (41a, 41b; 43) and the insertion portion (50, 51; 61) of the magnetic convergence ring holder (20A, 20B) in a counter-insertion direction, and the first inner surface (52, 53; 62a) is configured such that a distance between the first inner surface (52, 53; 62a) and the second inner surface (54, 55) facing the first inner surface (52, 53; 62a) decreases in the counter-insertion direction. a permanent magnet; a magnetic yoke (14A, 14B) disposed within a magnetic field formed by the permanent magnet, the magnetic yoke (14A, 14B) configured such that a position of the magnetic yoke (14A, 14B) relative to the permanent magnet varies; a magnetic convergence unit having a cylindrical shape, the magnetic convergence unit including a magnetic convergence ring holder (20A, 20B) having a cylindrical shape so as to surround the magnetic yoke (14A, 14B), a magnetic convergence ring (19A, 19B) attached to an inner peripheral surface of the magnetic convergence ring holder (20A, 20B) to collect a magnetic flux of the magnetic yoke (14A, 14B), and a magnetic shield fitted and attached onto an outer peripheral surface of the magnetic convergence ring holder (20A, 20B); and a magnetic sensor configured to detect a magnetic flux of a magnetic circuit formed by the permanent magnet, the magnetic yoke (14A, 14B), and the magnetic convergence ring (19A, 19B), wherein the outer peripheral surface of the magnetic convergence ring holder (20A, 20B) has an insertion portion (50, 51; 61) into which the magnetic shield is inserted when the magnetic shield is fitted onto the magnetic convergence ring holder (20A, 20B), and the magnetic shield has an inserting portion to be inserted into the insertion portion (50, 51; 61) of the magnetic convergence ring holder (20A, 20B) in an insertion direction, the inserting portion of the magnetic shield having an engaging member (41a, 41b; 43) that is always engaged with an inner surface of the insertion portion (50, 51; 61) of the magnetic convergence ring holder (20A, 20B) to restrict movement of the inserting portion of the magnetic shield in a counter-insertion direction during its insertion in the insertion portion (50, 51; 61) of the magnetic convergence ring holder (20A, 20B); characterized in that the insertion portion (50, 51; 61) of the magnetic convergence ring holder (20A, 20B) has a first inner surface (52, 53; 62a) and a second inner surface (54, 55) configured to restrict relative movement between the engaging member (41a, 41b; 43) and the insertion portion (50, 51; 61) of the magnetic convergence ring holder (20A, 20B) in a counter-insertion direction, and the first inner surface (52, 53; 62a) is configured such that a distance between the first inner surface (52, 53; 62a) and the second inner surface (54, 55) facing the first inner surface (52, 53; 62a) decreases in the counter-insertion direction.