An elevator renewal construction method includes a series of divided construction work steps, each being determined as such a unit that the elevator operation becomes normally possible after finishing of each of the divided construction work steps, wherein one of the series of the divided construction work steps comprises the steps of: replacing an old control panel of the existing elevator with a new control panel; connecting an old cable for an old car device, which has connected the old car device and the old control panel of the existing elevator to each other, to a communication conversion unit provided in the new control panel; and converting a new serial communication system to an old serial communication system by the new control panel via the communication conversion unit and the old cable to control the old car device through the old serial communication system.