Battery Module, Method for Manufacturing the Same, and Battery Pack

A battery module according to one embodiment of the present disclosure includes: a battery cell stack in which a plurality of battery cells are stacked, a first L-shaped frame accommodating the battery cell stack, and an upper part and one side surface of which are opened, and a second L-shaped frame accommodating the battery cell stack, and a lower part and one side surface of which are opened, wherein the first L-shaped frame and the second L-shaped frame are engaged with each other to surround four surfaces of the battery cell stack, a lower surface of the first L-shaped frame includes a first part and a second part, the first part is located at the edge with respect to a lengthwise direction of the battery cell, the second part is located in the interior of the first part, and a thickness of the first part is smaller than the thickness of the second part.