A steam generator includes a water chamber for holding water, the water chamber having a heater mounted thereto for heating the water, a steam chamber for holding steam generated as the water is heated, a water supply line for supplying the water to the water chamber, and a steam discharge line for discharging steam from the steam chamber, wherein the water chamber has a vertical direction length relatively greater than a horizontal direction length and the steam chamber has a horizontal direction length relatively greater than the horizontal length of the water chamber. A dryer or washing machine may include the steam generator described herein.