A battery module includes unit batteries each including long side surfaces and short side surfaces, with long side surfaces of adjacent unit batteries facing each other, a first spacer between the first unit battery and the second unit battery. A spacer includes a first side wall corresponding to a first short side surface of the first unit battery, the first side wall including a first hole through which fluid for cooling a bottom surface of the first unit battery is injectable, a bottom portion facing a bottom surface of the first unit battery, a support protrusion that spaces the bottom surface of the first unit battery apart from the bottom portion of the first spacer to provide a movement path of the fluid, and a second side wall at an opposite side of the first side wall, the second wall including a second hole through which the fluid is ejected.