Viscosity measurement device and measurement method therefor

This viscosity measurement device has: a container having a material to be measured placed therein; a spherical rotor formed from a conductive material, sinking into the material to be measured, and arranged so as to be in contact with the bottom section of the container; a magnet; a rotary magnetic field control unit; and a viscosity detection unit. The rotary magnetic field control unit controls the magnetic field such that: the magnet applies a rotary magnetic field to the rotor; an induction current is induced in the rotor: a rotation torque is applied to the rotor as a result of the Lorenz interaction between the induction current and the magnetic field applied to the rotor; and the rotor is caused to have circular movement corresponding to the rotation of the rotary magnetic field. The viscosity detection unit detects the viscosity of the material to be measured, by using the number of circuits of circular movement by the rotor.