A tool chucking apparatus to hold a machining cutter or tool includes a holding member and a fastening member that are coupled together to form a grip space inside to hold a collet. The collet has a plurality of pawl structures with a plurality of elastic slots formed thereon. When the holding member and the fastening member are coupled, the collet has one end tightly held in the holding member and the other end tightly held in the fastening member. Hence the two ends of the collet contract the elastic slots to tightly grip the cutter or tool. As a result, machining precision improves, safety enhances and the life span of the cutter or tool increases.