A washing machine and a method of controlling the same are disclosed. The amount of laundry that is introduced into the washing machine is measured using gravity and inertia applied during the operation of the motor (270), whereby it is possible to precisely calculate the amount of laundry and to minimize the effects of the initial position of the laundry and the movement of the laundry. In addition, the current value of the motor (270) that is operated is used to measure the amount of laundry without a sensor. Furthermore, the amount of laundry is measured at the rotational speed of the motor at which the laundry clings to the drum, whereby it is possible to minimize an error due to the movement of the laundry to thus improve accuracy. Moreover, it is possible to determine the amount of laundry within a short time. Consequently, it is easy to commence the spin-drying operation, thereby reducing washing time and saving energy.
