water tub 11 during the main washing cycle to top up the wash water to 100 of the desired amount the controller 130 drives the motor 15 based on a predetermined rpm and operation rate on off rate to rotate the rotary drum 12 as the rotary drum 12 rotates the main washing cycle is performed to wash laundry contained in the drum 12 using a force of gravity that results when the laundry falls as the drum rotates while allowing the main washing detergent to be mixed well with the wash water s 250 after that the remaining general cycles of the washing machine are successively performed s 260 and then the operation of the washing machine is finished as apparent from the above description the invention provides a washing machine and a washing control method thereof having the following effects firstly according to the invention it is possible to achieve not only an improvement in the efficiency of a preliminary washing cycle that is an optional function of the washing machine but also a reduction in the amount of detergent and wash water for use in the preliminary washing cycle secondly according to the invention the amount of detergent and wash water used for the preliminary washing cycle can be regulated this has the effect of achieving an improvement in wash performance by approximately 10 when the same amount of detergent as a conventional detergent supply method is used and also reducing the amount of detergent to be used by 15 while achieving the same wash effect as the conventional method as a result the amount of wash water to be used can be reduced by up to 50 although an embodiment of the invention has been shown and.