PURPOSE: To provide a leg for chair which is excellent in weight, strength, and rigidity and also producible with a relatively inexpensive production cost because of its large cavity.

CONSTITUTION: This synthetic resin made chair leg for a rotary chair is constituted of a cylindrical part having a center hole into which the shaft connected to the seat is fitted and a plurality of legs as a unit. The legs have hollow parts, respectively and bracings are formed to partition the respective hollow parts between the joint of adjacent legs and the cylindrical part forming the center hole.