To provide a drier capable of efficiently drying objects to be dried in a short time while maintaining air discharged to a housing chamber at a high temperature.

A washer-drier W provided with the housing chamber 10 for housing the objects to be dried for executing the operation of drying the objects to be dried inside the housing chamber 10 comprises: a gas cooler 82 as a heating means; an evaporator 85 as a dehumidifying means; a blower fan 83 as a blowing means; an air circulation route 72 for discharging the air heated by the gas cooler 82 into the housing chamber 10 by the blower fan 83, sending the air passed through the housing chamber 10 to the evaporator 85 and circulating it again to the gas cooler 82; and an openable and closable outdoor air introducing port 120 for mixing outdoor air in the air circulated inside the air circulation route 72.