In a plasma torch unit, copper rods forming a coil as a whole are disposed inside copper rod inserting holes formed in a quartz block so that the quartz block is cooled by water flowing inside the copper rod inserting holes and cooling water pipes. A plasma ejection port is formed on the lowermost portion of the torch unit. While a gas is being supplied into a space inside an elongated chamber, high-frequency power is supplied to the copper rods to generate plasma in the space inside the elongated chamber so that the plasma is applied to a substrate.