This paper investigates the motion of the air-oil interface of the FDBs of a non-operating HDD due to axial shock by experiment and simulation. The motion of the rotor with respect to stator and the oil leakage due to axial shock are investigated in the experiment. This research applies the finite volume method and the volume of fluid method to simulate the motion of fluid lubricant of FDBs due to the axial shock including two phase flow of air and oil. The thrust plate and shaft are assumed to move as a rigid body, and the surface tension at the air-oil interface is included. This research makes it possible to explain breakup phenomena of the air-oil interface of FBDs due to axial non-operating shock.