Disclosed is a heat sink having improved space utilization and a battery module including the same. The heat sink for cooling a cell assembly including at least one unit cell comprises a first heat sink coupled to one side of the cell assembly and having a first cooling channel through which a coolant passes, and a second heat sink coupled to the other side of the cell assembly and having a second cooling channel through which the coolant passes. Since heat sinks are coupled to both sides of a cell assembly, a Z-axial space of a battery pack may be ensured without increasing the height of the battery pack.