In an embodiment, there is provided a method of operating an electrostatic chuck of a plasma processing apparatus. The electrostatic chuck has a base, a dielectric layer formed on the base, and a chuck main body mounted on the dielectric layer. In the method, a temperature difference between the temperature of the base and the temperature of the chuck main body is reduced in a state in which the chuck main body is attracted to the dielectric layer with a relatively small electrostatic attractive force. In a case where the temperature difference between the temperature of the base and the temperature of the chuck main body becomes equal to or less than a predetermined value, the chuck main body is fixed to the base via the dielectric layer by a relatively large electrostatic attractive force.