A top-loading-type washing machine including a drum, a drive module for rotating the drum via a drive shaft, inner and outer pulsators placed in the drum so as to be rotated in opposite directions, and a gearbox connected to the drive shaft for rotating both the pulsators. The gearbox includes a sun gear rotatably connected to the drive shaft, planetary gears rotatably engaged with the sun gear, a ring gear rotatably engaged with the planetary gears, a carrier for connecting the planetary gears so as to be rotated along with the planetary gears, a gear housing to which the ring gear is fixed, the gear housing being coupled to the outer pulsator, and a carrier shaft coupled to the inner pulsator. The top-loading-type washing machine further includes a long-axis bolt fastened to the drive shaft and rotatably inserted into a carrier shaft bore of the carrier shaft.