PURPOSE: To provide a two stroke thermal insulation engine made of a low heat transmission material by forming a combustion chamber block for constituting an auxiliary chamber provided on a cylinder head, in a simple structure.

CONSTITUTION: A combustion chamber block 6 is arranged on a cylinder head 3, and it is manufactured with the low heat transmission ceramic material consisting of aluminum titanate so as to form a cylinder upper part 13 and a head lower surface part 14 in a integrated structure. An auxiliary chamber 1 opened to a cylinder 9 side is formed in the center part of the combustion chamber block 6, and the injection hole 25 of a fuel injection nozzle 5 is opened to the auxiliary chamber 1. It is thus possible to lower the heat transmission rate of the auxiliary chamber 1 sharply, and ensure extremely low heat transmission, and also ensure strength sufficiently as the auxiliary chamber 1 even if the auxiliary chamber 1 is manufactured with the low heat transmission material.