The invention relates to an intraoral splint (1) with a rear arch (2) to prevent snoring and apneas which prevents the possible shift of the tongue towards the rear part of the oral cavity of said user by means of the placement in the users maxilla, thereby preventing the possible blockage of the airway due to the superposition of the rear part of the tongue or soft palate on the posterior pharyngeal wall.The invention is particularly applicable in the otolaryngology sector where there is a need to correct said problems.