Method for manufacturing lithium ion battery

The present invention relates to a method for manufacturing a lithium ion battery having a set of a positive electrode current collector, a positive electrode active material layer, a separator, a negative electrode active material layer, and a negative electrode current collector laminated in this order, the lithium ion battery has a structure in which the outer peripheries of the positive electrode active material layer and the negative electrode active material layer are sealed by a sealing material and sealed in an electrolyte solution, and is characterized by having a step in which the positive electrode and/or the negative electrode are/is manufactured by an electrode manufacturing step. The electrode manufacturing step includes: a supply step of preparing a frame-shaped sealing material and a bottom surface member, and supplying an electrode active material composition containing electrode active material particles and an electrolyte solution to a space surrounded by the sealing material and the bottom