Battery module with improved fire protection performance

A battery module effectively suppresses a fire even when high-temperature gas or sparks are generated therein due to thermal propagation. The battery module includes a cell assembly configured such that secondary batteries having electrode leads are stacked in at least one direction; a module case configured to accommodate the cell assembly in an inner space thereof; a bus bar assembly located on at least one side of the module case and including a module bus bar made of an electrically conductive material and electrically connected to the electrode leads of the cell assembly and a bus bar housing configured so that the module bus bar is placed thereon and having a slot through which the electrode lead passes; and a blocking member located at the slot of the bus bar housing to close at least a portion of the slot by transforming a shape thereof when heat is applied thereto.