To provide an operation method for shortening the drying time of clothes and saving energy in a bathroom ventilation drier used in a general household.

A circulation fan 1 for sending hot air, a ventilation fan 2 for performing strong/weak ventilation operations inside a bathroom, a hot water control valve 3 for controlling the flow rate of hot water for heat exchange, a remote controller 4 with which a user performs operations and setting and a control means 5 for receiving signals from the remote controller 4 are provided. Then, when fixed time elapses after operation start, the ventilation fan 2 is switched from a strong operation to a weak operation by the control means 5. Thus, the bathroom ventilation drier for shortening the drying time of the clothes and saving the energy is obtained.