Disclosed is a cooling jacket configured to be disposed close to one surface of a battery cell to absorb heat of the battery cell, the cooling jacket including a cooling plate and a plurality of cooling channels extending therein. The plurality of cooling channels include a coolant supply manifold channel and a coolant discharge manifold channel respectively disposed at first and second sides of the cooling plate and each extending in a longitudinal direction from an inside of the cooling plate to an outside of the cooling plate so that one end thereof is exposed to the outside of the cooling plate; and non-uniform cooling channels spaced apart from each other by a predetermined distance and each having first and second ends respectively connected to the coolant supply manifold channel and the coolant discharge manifold channel, the non-uniform cooling channels having widths that are non-uniform in the longitudinal direction.