Abstract: A rod chucking device for a perforator for perforating a pig iron discharge opening being adapted to mount exchangeably perforating rods for perforation work, such as drill rods, blanking rods and the like to the tip end of an impact rod. The chucking device has a cotter movable between an engage position and disengage position in order to fix the perforating rod inserted into a rod insert hole of a socket. A spring is engaged with the cotter for urging the cotter toward the engage position. In order to prevent deterioration of the spring through vibration and heat during the operation, chilling air passage from the impact rod to the perforating rod is separated to form an air passage to chill the spring.