Provided is a sealing apparatus of a pouch-type secondary battery, capable of preventing electrolyte leakage by constantly positioning a lead on a sealing groove so as to completely seal the secondary battery. A sealing apparatus according to the present disclosure is a sealing apparatus of a pouch-type secondary battery which seals a pouch case in which an electrode assembly is installed. The sealing apparatus includes upper and lower sealing blocks, wherein at least one sealing block of the upper and lower sealing blocks has a sealing groove having a slanted step portion which is formed at a position corresponding to the lead of the pouch-type secondary battery and a lead guide for seating the lead on the sealing groove is installed in front of the sealing block.