A head drum assembly (200) of a tape recorder in which an inner race and an outer race of an upper bearing (250) are press-fitted onto a shaft (240) and a rotary drum (210), respectively, thereby applying a preload, and comprises preload means including a resilient body (270) such as a compressed coil spring that is disposed between a lower bearing (260) disposed between the rotary drum and the shaft and a stationary drum (220), the resilient body for upwardly pressing the inner race of the lower bearing, thereby applying a preload. Accordingly, the head drum assembly (200) of the tape recorder provides enhanced assembling efficiency and reduced manufacturing costs.