Carbon dioxide electrolytic device and method of electrolyzing carbon dioxide

A method for electrolyzing carbon dioxide, comprising:

• supplying carbon dioxide to a carbon dioxide supply flow path in an electrolysis cell, and supplying an electrolytic solution to a solution supply flow path in the electrolysis cell, the electrolysis cell having an anode, a cathode, the carbon dioxide supply flow path which supplies the carbon dioxide to the cathode, and the solution supply flow path which supplies the electrolytic solution to at least the anode among the cathode and the anode;
• supplying a current from a power supply connected to the anode and the cathode, to reduce carbon dioxide and thus produce a carbon compound in a vicinity of the cathode, and to oxidize water and thus produce oxygen in a vicinity of the anode;
• stopping the current supply from the power supply and the supply of the carbon dioxide and the electrolytic solution, based on request criteria of reduction performance of the electrolysis cell, and supplying a rinse solution to at least one of the solution supply flow path and the carbon dioxide supply flow path of the electrolysis cell;
• and
• measuring an electric conductivity of the rinse solution passed through the electrolysis cell by using a first electric conductivity meter provided on a discharge port side from the electrolysis cell of at least one of the solution supply flow path and the carbon dioxide supply flow path, and stopping the supply of the rinse solution based on a request criterion of the electric conductivity.