A high-resolution micro-torsion tester is developed based on electromagnetism, and the shear modulus of metallic glass fiber (Pd40Cu30Ni10P20) is measured using this tester. The torque is measured by a coil-magnet component and the rotation angle is measured by an inductive angular transducer. The calibration results show that the torque capacity of this tester is 1.1 x 10(-3) N m with resolution of 3 x 10(-8) N m and the rotation angle capacity is 90 degrees with a resolution of 0.01 degrees. A set of metallic glass fibers, with diameter of about 90 mu m, are tested using this tester. The average shear modulus is obtained as 20.2 GPa (+/- 6%).