A simultaneous ignition method for a hollow modular charge using a cluster laser according to the present invention can maximize an intensity of a laser beam per unit area radiated to a gunpowder coating part (39) by adjusting a path of the laser beam from first, second, third, fourth, fifth, and sixth laser oscillators (11, 12, 13, 14, 15, 16) igniting the gunpowder coating parts (39) through one-to-one matching with unit charges Nos. 1, 2, 3, 4, 5, and 6 (31, 32, 33, 34, 35, 36) having a charge inner diameter (38) as they goes away due to the linear arrangement of the unit charges Nos. 1, 2, 3, 4, 5, and 6 (31, 32, 33, 34, 35, 36), thereby simultaneously igniting a plurality of lasers in a cluster-shaped combination.