Abstract: Provided is a method of manufacturing a lithium secondary battery, in which, after filling a slurry containing a positive electrode active material in a plurality of pores of a metal foam, followed by performing a heat treatment process under an optimal condition, the positive electrode active material is firmly adhered in the plurality of pores of the metal foam, to thus prevent a positive electrode active material from being peeled off from the pores at the time of driving the lithium secondary battery, and increase reliability of the lithium secondary battery.