A washing machine and a control method therefor are provided. The washing machine includes a water tank, a washing tub, a pulsator, a drive motor, a coupling flange connected to the drive motor, a drive shaft that rotates the pulsator, a dewatering shaft that rotates the washing tub, a coupler configured to move up and down along the dewatering shaft and to be placed in a first position where the coupler engages the coupling flange and in a second position where the coupler is placed above the coupling flange, a solenoid module that moves the coupler, a coupler guide configured to be rotated by the coupler and fix the coupler in the second position, and a controller configured to control the solenoid module to move the coupler.