A drum type washing and drying machine has a water tank (4), a rotary drum rotatably provided in the water tank (5), a dehumidifying heat exchanger for dehumidifying air introduced from inside of the rotary drum (5), a heater unit for heating the air dehumidified by the dehumidifying heat exchanger, and a blower (131) for introducing the air in the rotary drum (5) into the dehumidifying heat exchanger and delivering into the rotary drum (5) the air heated by the heater unit. A filter (160) is placed in a suction-side channel between the rotary drum (5) and the blower and on an upstream side of air flow produced by the blower (131) in a drying process. The filter (160) is placed so as to be soaked in water supplied into the water tank in a washing process or in a rinsing process.