A cooling plate and a plasma processing chamber are proposed. The cooling plate is configured to allow air to flow throughout the entire region of a window while reducing a region of covering the window. The cooling plate is configured to cool a window configured to seal a plasma processing space at an upper portion, and the cooling plate includes a body having a circular plate shape covering a part of a center region of the window, an inlet through which a gas is introduced into the body, and an outlet through which the gas is discharged from the body to the window. A flow path through which the gas flows and a slope formed from the flow path toward the window are formed between the inlet and the outlet.