A secondary battery module and a battery spacer, the secondary battery module including a plurality of unit cells; and a battery spacer between the unit cells, the battery spacer including a base portion, the base portion including a portion contacting a large side surface of a unit cell, a wing portion projecting from the base portion toward an adjacent battery spacer and enclosing at least a portion of a small side surface of the unit cell, and a fastening portion on the wing portion, the fastening portion being for coupling the battery spacer to an adjacent battery spacer.