An apparatus for treating athlete's foot includes an inner box placed in an outer box, and having a space between the internal walls of the outer box and the external walls of the inner box. The interior of the inner box serves as an aerosol chamber. A heat source is provided in the lower part of the aerosol chamber, and an aerosol generating plate is placed thereon. An ultrasonic-wave oscillator, directed toward the interior of the aerosol chamber, is attached to the ceiling of the aerosol chamber. An exhaust port communicating with the interior of the outer box is provided in the upper part of the aerosol chamber. An exhaust filter and an exhaust fan are provided in the upper part of the outer box. A common opening through which the part affected with athlete's foot is to be inserted is provided in one side of both the outer and inner boxes. The common opening is closed with a sealing member. The space between the outer and inner boxes prevents the heat generated within the inner box from being transmitted outside. The exhaust fan and filter attached to the outer box absorb, filter, and expel the aerosol generated in the inner box, preventing the smell of the aerosol from leaking outside.