The present invention relates to a die-casting apparatus which cools metals after hot pressing. More specifically, disclosed is a die-casting apparatus using immersion cooling, wherein a die is immersed into a cooling medium for improving the cooling speed of the die and securing uniform quality. The die-casting apparatus includes: an upper mold provided with a casting surface on the bottom aspect; a lower mold provided with a casting surface on the top aspect; a cooling water tub storing a cooling medium at a predetermined level; and a press means for lowering and compressing the upper mold against the lower mold, and subsequently, lowering the upper and lower molds in the compressed state, and lifting the molds in the reverse sequence.