PURPOSE: To proceed with construction work while stopping an elevator short time by short time to replace an existing landing door, a landing door opening/ closing device, and a car door opening/closing device with new ones by dividing the work of replacing the landing door and the door opening/closing devices.

CONSTITUTION: First, a landing door 13, a door hanger 14, and a landing door opening/closing device are replaced with new devices. For this, mounting holes for an existing landing engaging element 6, temporary and new door locks 17, 30 or the like can be previously shop machined whereby on-site working time, i.e., the period of stopping an elevator, can be reduced. Since the landing door opening/closing device or the like is replaced first, the landing door opening/closing device or the like can be transported by an existing car. Thus, the work of replacing the landing door 13 and the door opening/closing device is divided, and by proceeding with construction work while stopping the elevator short time by short time, the devices can be replaced with new ones while allowing for the convenience of elevator users.