Abstract: The inventive concept provides a substrate treating apparatus. The substrate treating apparatus includes a housing having a treating space treating a substrate; a support unit supporting the substrate at the treating space; a gas supply unit supplying a process gas into the treating space; and a plasma source generating a plasma from the process gas, and wherein the support unit comprises: a dielectric plate placing the substrate on a top surface thereof; a top ring surrounding a circumference of a substrate placed on the dielectric plate; a temperature sensor measuring a temperature of the top ring; a first lifting/lowering member lifting/lowering the top ring; and a controller, and wherein the controller controls the first lifting/lowering member to change a height of the top ring according to an etching amount of the top ring calculated based on the temperature of the top ring measured by the temperature sensor.