A drum type washing machine includes a rotatable drum adapted to store a laundry, a drain valve, a drain pump, a controller, and a filter unit. The filter unit includes a filter case provided betweenthe drain valve and the drain pump, a filter accommodated in the filter case, a cap for sealing a fixing opening, and a reed switch. The reed switch is activated to outputs an activation signal to thecontroller when the cap is located at the predetermined position, and deactivated to output a deactivation signal to the controller when the cap is not at the predetermined position. The controller is operable to, when determining that the reed switch outputs the deactivation signal while executing a process out of the washing process and the rinsing process, stop the process. The controller is operable to, when determining that the reed switch outputs the deactivation signal while executing the draining process, stop the draining process, close the drain valve, and drive the drain pump. Thiswashing machine prevents washing water from leaking and safely washes the laundry even when the filter is opened during the washing process, the rinsing process, and the draining process.