A capacitively coupled plasma processing apparatus includes a chamber; a gas supply that supplies an inert gas into the chamber; a substrate support including a lower electrode; an upper electrode provided above the substrate support and including silicon; a first radio-frequency power supply electrically connected to the upper electrode; a second radio-frequency power supply electrically connected to the lower electrode; a bias power supply that applies a negative bias voltage to the upper electrode; and a controller that controls an overall operation of the capacitively coupled plasma processing apparatus such that the silicon-containing material is deposited on sidewalls of a mask of the substrate to narrow an opening formed on the mask by an amount greater in a second direction than in a first direction.