In a hydrodynamic bearing type rotary device, relationships between the number of times of intermittence life, a bearing load, lubricating fluid viscosity, a bearing size, and the like are considered in order to provide a hydrodynamic bearing type rotary device which can secure appropriate intermittence life. In a hydrodynamic bearing type rotary device, a shaft is inserted into a bearing hole of a sleeve so as to be relatively rotatable. A value of a function (Nd) is set to be 100,000 or higher: wherein Nd=η/(S·Ff·P·D).