The present invention relates to a secondary battery. The secondary battery comprises: an electrode assembly having a through-hole; and a battery case accommodating the electrode assembly and having a through-type opening into which the through-hole is inserted, wherein the battery case comprises: a lower case comprising an accommodation part accommodating the electrode assembly and a lower inner sealing part having the through-type opening into which the through-hole is inserted; and an upper case comprising a cover part coupled to an upper portion of the lower case to finish the accommodation part and an upper inner sealing part having a coupling hole to which a front end of the lower inner sealing part is coupled.