  Viscosity measurements in combination with pulsed magnetic fields are
developed by use of a quartz-crystal microbalance (QCM). When the QCM is
immersed in liquid, the resonant frequency, $f_0$, and the quality factor, $Q$,
of the QCM change depending on $(\rho\eta)^{0.5}$, where $\rho$ is the mass
density and $\eta$ the viscosity. During the magnetic-field pulse, $f_0$ and
$Q$ of the QCM are simultaneously measured by a ringdown technique. The typical
resolution of $(\rho\eta)^{0.5}$ is 0.5 %. As a benchmark, the viscosity of
liquid oxygen is measured up to 55 T.
