To provide a vacuum insulated triangular pipe capable of preventing reduction of temperature and reducing flow resistance and energy loss.

This vacuum insulated pipe is manufactured by adding three triangular pipes evacuated to have insulation and having a limited length to an outer side of the triangular pipe for letting a liquid flow in it by letting the four pipes adhere closely to one another. In another embodiment, the vacuum insulated pipe is constituted by covering the triangular pipe with the round pipes by letting them adhere closely to the triangular pipe, making a clearance between the triangular pipe and the round pipe vacuum and thermally insulated, and letting the liquid flow in it to insulate heat by utilizing the vacuum state.