A yoke cover for use in a torque detection device including paired detection coils having impedance varied by torque generated at a rotary shaft and configured to detect the torque in accordance with output voltage of the detection coils , the single yoke cover interposed between two electromagnetic yokes axially facing each other and fitted to inner circumferences of cylindrical portions of the two electromagnetic yokes to retain the two electromagnetic yokes , the yoke cover comprising: a first cylindrical surface fitted to first one (11 a) of the two electromagnetic yokes and provided in each of a plurality of first circumferential portions (F1) in an outer circumferential surface (F), and a second cylindrical surface fitted to second one of the two electromagnetic yokes and provided in each of a plurality of second circumferential portions (F2) circumferentially displaced from the first circumferential portions (F1) in the outer circumferential surface (F); and a corner radius portion provided at a portion axially closer to the first one of the electromagnetic yokes than each of the first cylindrical surfaces , at the first circumferential portion (F1) to which the first cylindrical surface is fitted, the portion axially closer to the second one of the electromagnetic yokes than each of the first cylindrical surfaces has a tapered surface gradually reduced in outer diameter as axially distant from an axial edge of each of the first cylindrical surfaces , a corner radius portion provided at a portion axially closer to the second one of the electromagnetic yokes than each of the second cylindrical surfaces , at the second circumferential portion (F2) to which the second cylindrical surface is fitted, and the portion axially closer to the first one of the electromagnetic yokes than each of the second cylindrical surfaces has a tapered surface gradually reduced in outer diameter as axially distant from an axial edge of each of the second cylindrical surfaces . a first cylindrical surface fitted to first one (11 a) of the two electromagnetic yokes and provided in each of a plurality of first circumferential portions (F1) in an outer circumferential surface (F), and a second cylindrical surface fitted to second one of the two electromagnetic yokes and provided in each of a plurality of second circumferential portions (F2) circumferentially displaced from the first circumferential portions (F1) in the outer circumferential surface (F); and a corner radius portion provided at a portion axially closer to the first one of the electromagnetic yokes than each of the first cylindrical surfaces , at the first circumferential portion (F1) to which the first cylindrical surface is fitted, the portion axially closer to the second one of the electromagnetic yokes than each of the first cylindrical surfaces has a tapered surface gradually reduced in outer diameter as axially distant from an axial edge of each of the first cylindrical surfaces , a corner radius portion provided at a portion axially closer to the second one of the electromagnetic yokes than each of the second cylindrical surfaces , at the second circumferential portion (F2) to which the second cylindrical surface is fitted, and the portion axially closer to the first one of the electromagnetic yokes than each of the second cylindrical surfaces has a tapered surface gradually reduced in outer diameter as axially distant from an axial edge of each of the second cylindrical surfaces . <EOS>