performing the selected washing course are set then according to the use amount of liquid detergent which was set at the use amount setting process s 100 the liquid detergent is supplied at step s 160 then a washing process is performed by the washing device 50 here since the process of performing a washing process using the washing device 50 may be easily understood by those skilled in the art the detailed descriptions thereof are omitted herein meanwhile the control unit 80 calculates a total use amount of liquid detergent by adding up the supplied amounts of liquid detergent at step s 170 when the total use amount of liquid detergent is calculated the total use amount of liquid detergent is compared to the preset reference amount so as to determine whether the total use amount of liquid detergent is equal to or more than the reference amount at step s 180 as a determination result when the total use amount of liquid detergent is equal to or more than the reference amount the control unit 80 controls the warning unit 60 to issue a warning for the residual amount of liquid detergent at step s 190 meanwhile when the total use amount of liquid detergent is less than the reference amount whether or not to perform the next washing process is checked when the use amount of liquid detergent is not set at the use amount setting process s 100 whether or not a washing command is inputted through the washing command input key 11 is checked at step s 110 when the washing command input key 11 is inputted a laundry amount is detected through the laundry amount detection unit 40.