A disclosed heater for a sealing process of a secondary battery includes: a sealing bar heating and pressing a pouch foil to be sealed; a plurality of sub-heating unit longitudinally disposed inside the sealing bar to respectively independently supply heat to a plurality of sections separated in the longitudinal direction of the sealing bar; temperature sensing units disposed inside the sealing bar and sensing temperature at positions on the surfaces being in contact with the pouch foil; and a control unit controlling heating temperature of the plurality of sub-heating units on the basis of the temperature sensed by the temperature sensing units.