A combined externally pressurized gas and magnetic bearing assembly (3) includes an externally pressurized gas bearing (9) and a magnetic bearing (8) that are integrated together so as to have component parts common to both of the externally pressurized gas bearing (9) and the magnetic bearing (8). The externally pressurized gas bearing (9) or the magnetic bearing (8) may be disposed within an axial extent of the magnetic bearing (8) or the externally pressurized gas bearing (9), respectively. A spindle device utilizing the combined externally pressurized gas and magnetic bearing assembly (3) is also provided which includes a housing for supporting a main shaft (4) rotatably through the combined externally pressurized gas and magnetic bearing assembly (3). This combined externally pressurized gas and magnetic bearing assembly (3) can be applied not only to the radial bearing, but also to the axial bearing.