A dental suction assisting device includes an upper molar seat located at an upper portion of a body and having anti-separation protrusions and a space for allowing seating of upper molars, a lower molar seat located at a lower portion of the body and having anti-separation protrusions and a space for allowing seating of lower molars, a fastening portion having an insertion hole and a through-hole and allowing fastening of a suction tube, a suction port having a first suction hole and allowing secretions in an oral cavity to be sucked through the suction tube, a leg formed at each side of the lower molar seat, configured such that the respective legs are brought into intimate contact with opposite side surfaces of the lower molars and having partitions, and a wing extending from the leg, and seated between the lower molars and skin in the oral cavity.