CYLINDER BORE WALL INSULATOR, INTERNAL COMBUSTION ENGINE, AND AUTOMOBILE

There is provided a thermal insulator for a cylinder bore wall for insulating a bore wall facing a coolant inflow port to the groove-like coolant passage, the thermal insulator including: a rubber member in contact with a wall surface on a cylinder bore side of the groove-like coolant passage and for covering the wall surface on the cylinder bore side of the groove-like coolant passage; and a metal base member to which the rubber member is fixed, wherein the metal base member includes: a rear surface pressing part; elastic parts; and a movement limiting part extending from a rear surface of the metal base member toward a lower portion of an inside of the coolant inflow port in the cylinder block, and having an extending end positioned outside a position of a wall surface outside the groove-like coolant passage, and for limiting a movement of the metal base member.There can be provided a thermal insulator for a cylinder bore wall, for insulating a cylinder bore wall facing a coolant inflow port to a groove-like coolant passage, and capable of limiting a movement in an up-down direction and a circumferential direction of the groove-like coolant passage.