An apparatus for checking insulation of a cell module assembly composed of a plurality of pouch cells includes a first probing unit electrically contacted to an electrode of the cell module assembly; a second probing unit electrically contacted to aluminum films of selected ones of the pouch cells in the cell module assembly; and a measuring unit for measuring an insulation resistance between the first probing unit and the second probing unit. This apparatus may measure insulation resistances of a plurality of pouch cells of the cell module assembly at once, thereby ensuring faster insulation checking.