Unbalance detection method and washing machine using the same

A washing machine and unbalance detection method using the same, which is capable of efficiently detecting unbalance of a rotation tub. A washing machine includes: a washing motor rotating a rotation tub accommodating laundry; a motor velocity detection unit detecting a velocity of the washing motor and outputting a motor velocity signal; and a controller determining whether unbalance of the rotation tub occurs according to an unbalance level determined on the basis of a velocity ripple of the motor velocity signal, and controlling the washing motor according to the determination result. A method of detecting unbalance of a rotation tub accommodating the laundry in a washing machine includes: driving a washing motor in order to rotate the rotation tub; detecting a velocity of the washing motor, and outputting a motor velocity signal; extracting a velocity ripple of the motor velocity signal, the velocity ripple being generated while detecting the velocity of the washing motor; operating the extracted velocity ripple, and detecting an unbalance level; and comparing the detected unbalance level with a reference value, and determining whether the unbalance of the rotation tub occurs.