A spin cycle controlling apparatus for a washing machine comprising: a storage unit in which an acceleration rate, an allowable maximum unbalance amount and an allowable minimum unbalance amount according to an amount of laundry are pre-stored; and a controlling unit for repeatedly controlling an operation of increasing and decreasing revolutions per minute in a region between the allowable maximum unbalance amount and the allowable minimum unbalance amount until an unbalance amount detected is less than the allowable minimum unbalance amount, wherein the region between the allowable maximum unbalance amount and the allowable minimum unbalance amount is set between a clothes centrifugally-distributed region and a clothes tumbling region for evenly distributing laundry; wherein when the unbalance amount detected is less than the allowable minimum unbalance amount, the controlling unit increases the RPM of the washing machine and then applies a separate reference unbalance amount thus to perform the spin cycle, characterized in that the controlling unit increases the RPM of the washing machine to detect a first unbalance amount at a first target speed, and increases the RPM by a certain acceleration to detect a second unbalance amount when the first unbalance amount is less than a first reference unbalance amount (SP4, SP5), the controlling unit repeatedly increases or decreases the RPM until the second unbalance amount is less than the allowable minimum unbalance amount (SP7, SP8), and the controlling unit increases the RPM up to a second target speed when the second unbalance amount becomes lass than the allowable minimum unbalance amount within a certain time, wherein when a third unbalance amount detected at the second target speed becomes less than a second reference unbalance amount, the controlling unit than increases the RPM of the washing machine to thus perform a spin cycle. a storage unit in which an acceleration rate, an allowable maximum unbalance amount and an allowable minimum unbalance amount according to an amount of laundry are pre-stored; and a controlling unit for repeatedly controlling an operation of increasing and decreasing revolutions per minute in a region between the allowable maximum unbalance amount and the allowable minimum unbalance amount until an unbalance amount detected is less than the allowable minimum unbalance amount, wherein the region between the allowable maximum unbalance amount and the allowable minimum unbalance amount is set between a clothes centrifugally-distributed region and a clothes tumbling region for evenly distributing laundry; wherein when the unbalance amount detected is less than the allowable minimum unbalance amount, the controlling unit increases the RPM of the washing machine and then applies a separate reference unbalance amount thus to perform the spin cycle, characterized in that the controlling unit increases the RPM of the washing machine to detect a first unbalance amount at a first target speed, and increases the RPM by a certain acceleration to detect a second unbalance amount when the first unbalance amount is less than a first reference unbalance amount (SP4, SP5), the controlling unit repeatedly increases or decreases the RPM until the second unbalance amount is less than the allowable minimum unbalance amount (SP7, SP8), and the controlling unit increases the RPM up to a second target speed when the second unbalance amount becomes lass than the allowable minimum unbalance amount within a certain time, wherein when a third unbalance amount detected at the second target speed becomes less than a second reference unbalance amount, the controlling unit than increases the RPM of the washing machine to thus perform a spin cycle.