A control method of a washing machine comprising: sensing a first unbalance amount of a drum in which laundry is received while rotating the drum at a first rotational velocity, wherein the first unbalance amount is judged based on whether the variation range of the actual rotational velocity of the drum is within a boundary value; sensing a second unbalance amount of the drum while accelerating the drum to a second rotational velocity, when the first unbalance amount is allowed; and accelerating the drum to a target rotational velocity, when the second unbalance amount is allowed, characterized in that, in the step of sensing a second unbalance amount of the drum, the second unbalance amount is judged based on whether the variation range of the actual rotational velocity of the drum is continuously decreased, and in that the method further comprises: sensing a third unbalance amount of the drum while accelerating the drum to a third rotational velocity, when the second unbalance amount is not allowed until the drum reaches the second rotational velocity, wherein the third unbalance amount is judged based on whether the variation range of the actual rotational velocity of the drum is continuously decreased, and wherein the acceleration of the drum when the third unbalance amount is sensed is lower than the acceleration of the drum when the second unbalance amount is sensed. sensing a first unbalance amount of a drum in which laundry is received while rotating the drum at a first rotational velocity, wherein the first unbalance amount is judged based on whether the variation range of the actual rotational velocity of the drum is within a boundary value; sensing a second unbalance amount of the drum while accelerating the drum to a second rotational velocity, when the first unbalance amount is allowed; and accelerating the drum to a target rotational velocity, when the second unbalance amount is allowed, characterized in that, in the step of sensing a second unbalance amount of the drum, the second unbalance amount is judged based on whether the variation range of the actual rotational velocity of the drum is continuously decreased, and in that the method further comprises: sensing a third unbalance amount of the drum while accelerating the drum to a third rotational velocity, when the second unbalance amount is not allowed until the drum reaches the second rotational velocity, wherein the third unbalance amount is judged based on whether the variation range of the actual rotational velocity of the drum is continuously decreased, and wherein the acceleration of the drum when the third unbalance amount is sensed is lower than the acceleration of the drum when the second unbalance amount is sensed. sensing a third unbalance amount of the drum while accelerating the drum to a third rotational velocity, when the second unbalance amount is not allowed until the drum reaches the second rotational velocity, wherein the third unbalance amount is judged based on whether the variation range of the actual rotational velocity of the drum is continuously decreased, and wherein the acceleration of the drum when the third unbalance amount is sensed is lower than the acceleration of the drum when the second unbalance amount is sensed.