A heater supporting device for use in a semiconductor manufacturing apparatus is provided so as to improve the uniformity of a temperature property and the expected lifespan by preventing support pieces from being damaged and separated from piece holders, and preventing deterioration in adiabatic efficiency in the vicinity of a ceiling of a vertical type furnace. A heating element of a coil shape is disposed around an object. The support pieces are vertically connected in multiple. Hollows of an elliptical shape are formed between the respective support pieces. Concave insertions are formed on one of upper and lower surfaces of the respective support pieces, and convex insertions are formed on the other one of the upper and lower surfaces of the respective support pieces. The convex insertions are insert-fitted with the concave insertions. The support pieces are vertically connected in multiple by insert-fitting the concave insertions to the convex insertions.