A battery module having a cell stack in which a plurality of battery cells are stacked; a housing having an accommodation space in which the cell stack is accommodated, wherein the accommodation space comprises an open end; a flow path forming compartment covering the open end and comprising an inlet, an outlet, and a flow path forming member ; and a flame blocking member installed in the flow path forming compartment, wherein a first area of a first side opposite to the cell stack among sides of the flow path forming compartment has a value greater than a second area second side opposite to the cell stack among sides of each of the sidewalls.