A substrate transfer mechanism for transferring a substrate includes a mounting table on which the substrate is mounted; an arm member connected to the mounting table and moving it. The substrate transfer mechanism further includes a temperature control unit for controlling temperature of the mounting table, wherein the temperature control unit forms a temperature gradient in the mounting table. The temperature control unit includes a detector for detecting temperature in an environment or a chamber in which the substrate transfer mechanism is installed a heater for heating the mounting table and a controller for controlling an operation of the heater based on the temperature in the environment or the chamber detected by the detector.