To shorten the drying time for washing, and to finish the washing in a fluffy state without creases and shrinkage.

This washing and drying machine includes two drums as a decompression tub and a spin-drying and washing tub. In a drying process, first the temperature of water adhering to the clothes in the spin-drying and washing tub is raised to 30 to 60°C, subsequently hot air is stopped, and the decompression tub is rotated at a high speed to lower the pressure to 4.6 to 31.8 mmHg. Thus, the boiling point of the spin-drying and washing tub reaches 0 to 30°C so that the water adhering to the clothes starts to evaporate at a high speed. The evaporated water is drained from the decompression tub to the outside. When a thermometer disposed inside or outside the decompression tub detects 0 to 30°C, the decompression tub is stopped or rotated at medium speed. After the decompression tub is returned to the ordinary pressure and the hot air is blown into the tub to raise the temperature to 30 to 60°C, again the decompression tub is rotated at a high speed and the boiling point in the decompression tub and the spin-drying and washing tub is lowered to 0 to 30°C to accelerate evaporation of water adhering to the clothes. The above operation is repeated to shorten the drying time.