A magnetic fluid simultaneously has hydrodynamic and electromagnetic properties because its characteristics depend on whether a magnetic field is applied or not. The studies conducted so far on actuators that use a magnetic fluid are insufficient. A magnetic fluid has an added advantage in that it can be applied to small or micro systems because of its nanoscale particle size. Therefore, this research investigated the braking characteristics of a small disk brake that used a magnetic fluid. First, magnetostatic analysis of the magnetic field produced by a permanent magnet was conducted, and then, the pressure distribution in the magnetic acted upon by the magnetic body force from the permanent magnet was analyzed using the governing equations of a magnetic fluid. So, in this research, the torque characteristic of small disk brake by a magnetic body force was studied through the relation between the magnetic field intensity and rotational disk velocity. In addition, the torque characteristics of the brake due to a magnetization of the magnetic fluid were confirmed experimentally.