The present invention is a method for manufacturing a secondary battery. An electrode assembly and an electrolyte are accommodated into a body of a battery case. The body of the battery case has an accommodation part and a gas pocket part, and a passage that extends from the accommodation part to the outside discharges an internal gas from the accommodation part through the gas pocket part. The battery case is seated in a seating step on a support block, which has an inclined part on a side surface thereof, to support the battery case. The body is pressed to discharge a gas accommodated in the accommodation part through the gas pocket part in the battery case. This method allows easy discharging of internal gas while reducing discharge of the electrolyte with the gas.