A heating apparatus for cooking using steam and a method of controlling the same. The heating apparatus includes a main body having a cooking chamber; a steam-generating device for supplying steam to the cooking chamber; and a water supply device for supplying water to the steam-generating device, having a water bucket for containing water; a water bucket-supporting device installed on the main body for supporting the water bucket, and including a space for containing an inlet of the water bucket such that the inlet can be soaked in the water when the water bucket is inserted into the water bucket-supporting device such that the inlet of the water bucket faces a bottom of the bucket-supporting device; a water supply pump for supplying the water of the water bucket-supporting device to the steam-generating device; and water supply pipes for guiding the water from the water bucket-supporting device to the steam-generating device. The method controls removal of residual water of the steam-generating device and the water supply device, and a time for supplementing water of the water supply device.