To provide a molar tooth protector of a structure which is stably mountable, lessens foreign matter feel at the time of mounting and is easy to bite.

The molar tooth protector to be used by being mounted at the teeth on a lower side along the dentition consists of a detaining part 3 which is formed to an approximately U shape along the dentition so as to cover the rear side of the teeth and a protective part 5 which is disposed successively at both right and left ends of the detaining part 3 and covers the occlusal surfaces of the right and left molar teeth. At both top and bottom end face parts of the protective part 5 are formed of a thermoplastic resin having the softening temp. higher than the body temp. of man and lower than the boiling temp. of water. Both right and left ends of the detaining part are formed to an arcuate shape so as to incline upward toward the rear side which is a back tooth side. The falling angle α at the rear end of the detaining part from the protective part 5 is set at about 135 to 165° with the rear surface at the rear end of the protective part.