A heat insulating vessel for a low temperature liquefied gas pump, which includes an inner tank configured to accommodate low temperature liquefied gas, an outer tank provided externally around the inner tank, and a low temperature liquefied gas pump disposed inside the inner tank. The outer tank has an outer tank upper part that is an upper end portion thereof, and an outer tank body other than the outer tank upper part. A lid structure having a heat-insulated structure detachably fitted into an upper part of the inner tank. The pump is fixed to the lid structure, and a suction pipe and a discharge pipe are insertedly fixed to the lid structure. A vacuum insulating layer is provided between the inner tank and the outer tank. With this heat insulating vessel for the low temperature liquefied gas pump, adiabaticity of the lid structure and maintainability of the pump are increased.