Wafer processing with no dummies is sets forth, wherein an apparatus includes: a boat that hold a product substrates in array at all of positions where substrates may be held; a tubular reactor that houses the boat; a furnace surrounding an upper side and a lateral side of the reactor; a heater provided in the furnace and adapted to heat a side portion of the reactor; a ceiling heater provided in the furnace and adapted to heat a ceiling of the reactor; and a cap heater provided inside the reactor and below the boat; a gas supply mechanism individually supplying a gas to a top side of each of the product substrates.