Washing machine and method of controlling the same, wherein the amount of laundry that is introduced into the washing machine is measured using gravity and inertia applied during the operation of a motor (270) and a current value of the motor (270) that is operated is used to measure the amount of laundry without a dedicated sensor, whereby the rotational speed of the motor (270) is controlled stepwise from a low speed (S1) and the characteristics of gravity in the low-speed maintenance period and the characteristics of inertia in the acceleration period are used to calculate the amount of laundry.
