Plating apparatus

A plating apparatus comprising:

• a plating tank;
• a substrate holder that holds a substrate;
• an anode disposed in the plating tank to oppose the substrate held by the substrate holder;
• a conduit having a first portion including an opening end disposed in a region between the substrate held by the substrate holder and the anode, and a second portion apart from the region between the substrate held by the substrate holder and the anode, the conduit having at least a part filled with a plating solution;
• a first detection electrode that is a potential sensor disposed in the second portion of the conduit, and configured to measure a potential of the plating solution;
• a second detection electrode that is a potential sensor for reference, the second detection electrode disposed at a second position and configured to measure potential of the plating solution outside of a region between the substrate and the anode as compared to the opening end in the plating tank;
• and
• a control module that measures a potential difference between the first detection electrode and the second detection electrode, to estimate a thickness of a plating film on the substrate based on the potential difference.