Abstract: A lithium secondary battery including: an inner electrode member having electrode plates (cathode plate and anode plate) of a metal foil as a constituting element, and being formed by winding or laminating electrode plates; and a battery case for housing the inner electrode member. A gas release channel capable of releasing a gas to the outside of the battery case is formed by deformation of the inner electrode member by a function of a raised inner pressure when the inner pressure of the battery case rises to a predetermined pressure or more due to the gas generated inside the inner electrode member. The lithium secondary battery can smoothly release the gas generated inside the inner electrode member without being retained therein before the gas reaches a pressure releasing mechanism; thus, it is superior in safety and has a high energy density.