The present invention pertains to a substrate etching device that can uniformly etch the entirety of a substrate surface and that has increased uniformity of in-plane density of generated plasma. The plasma etching device (1) is provided with: a chamber (2) at which a plasma generation space (3) and a processing space (4) are set; a coil (30) that is disposed at the outside of an upper body section (6); a base (40) for substrate (K) placement disposed in the processing space (4); an etching gas supply mechanism (25) for supplying etching gas to the plasma generation space (3); a coil power supply mechanism (35) for supplying high-frequency power to the coil (30); and a base power supply mechanism (45) for supplying high-frequency power to the base (40). Also, a plasma density adjustment member (20) having a tapered shape is affixed to the inner wall of the chamber (2) between the plasma generation space (3) and the base (40), and furthermore, a tubular core member (10) is provided extending downwards from the top of the chamber (2) and at which is formed a tapered section that has a smaller diameter towards the bottom surface thereof.
