A fluid dynamic bearing device , comprising: a housing formed into a bottomed cylindrical shape so as to have one open axial end and another closed axial end; a bearing sleeve fixed to an inner periphery of the housing ; a shaft member removably inserted along an inner periphery of the bearing sleeve ; an annular member having an inner peripheral surface for defining a radial gap (Ga) together with an outer peripheral surface of the shaft member , the annular member being fixed to an inner periphery of the one open axial end of the housing 87) in a state of engaging with the bearing sleeve 88) in an axial direction; a radial bearing portion (R1, R2) for supporting the shaft member in a radial direction by an oil film of lubricating oil , which is formed in a radial bearing gap (Gr) defined between an inner peripheral surface of the bearing sleeve and the outer peripheral surface of the shaft member ; a thrust bearing portion (T) for supporting the shaft member in a thrust direction; and a bottom gap (Gb) having the thrust bearing portion (T) received therein, and being filled with the lubricating oil , wherein the housing has a void section formed in an interior space thereof, the void section being not filled with the lubricating oil , wherein assuming that d 1 represents a gap width of the radial bearing gap (Gr) and d 2 represents a gap width of the radial gap (Ga), a relationship of 30d 1 ≤d 2 ≤250d 1 is satisfied, and wherein under a state in which a standing position that the one open axial end of the housing is arranged on the upper side in a vertical direction and the another closed axial end of the housing is arranged on the lower side in the vertical direction, an oil level of the lubricating oil is maintained in an annular space that is defined between an inner circumferential chamfer which is arranged on an one axial end of the bearing sleeve and the outer peripheral surface of the shaft member . a housing formed into a bottomed cylindrical shape so as to have one open axial end and another closed axial end; a bearing sleeve fixed to an inner periphery of the housing ; a shaft member removably inserted along an inner periphery of the bearing sleeve ; an annular member having an inner peripheral surface for defining a radial gap (Ga) together with an outer peripheral surface of the shaft member , the annular member being fixed to an inner periphery of the one open axial end of the housing 87) in a state of engaging with the bearing sleeve 88) in an axial direction; a radial bearing portion (R1, R2) for supporting the shaft member in a radial direction by an oil film of lubricating oil , which is formed in a radial bearing gap (Gr) defined between an inner peripheral surface of the bearing sleeve and the outer peripheral surface of the shaft member ; a thrust bearing portion (T) for supporting the shaft member in a thrust direction; and a bottom gap (Gb) having the thrust bearing portion (T) received therein, and being filled with the lubricating oil , wherein the housing has a void section formed in an interior space thereof, the void section being not filled with the lubricating oil , wherein assuming that d 1 represents a gap width of the radial bearing gap (Gr) and d 2 represents a gap width of the radial gap (Ga), a relationship of 30d 1 ≤d 2 ≤250d 1 is satisfied, and wherein under a state in which a standing position that the one open axial end of the housing is arranged on the upper side in a vertical direction and the another closed axial end of the housing is arranged on the lower side in the vertical direction, an oil level of the lubricating oil is maintained in an annular space that is defined between an inner circumferential chamfer which is arranged on an one axial end of the bearing sleeve and the outer peripheral surface of the shaft member . <EOS>