A head drum assembly for a tape recorder maintains a substantially constant preload and reduces manufacturing costs. The head drum assembly includes a shaft fixed to a center of a stationary drum, a rotary drum installed to an upper portion of the stationary drum to be rotated by the shaft and having a rotor, a stator installed to an upper portion of the rotary drum to face the rotor, a bearing interposed between the shaft and the rotary drum that rotatably supports the rotary drum, a spring resiliently supporting an inner race of the bearing, and a drum cover fixed with the stator and fixed to the shaft to apply a substantially constant pressure to the bearing and to substantially constantly maintain a spacing between the stator and the rotor.