Ozone water concentration measurement apparatus and ozone water concentration measurement method

Disclosed is an ozone water concentration measurement apparatus (100) that is capable of measuring ozone concentrations with high accuracy and without using an electrolyte. The ozone water concentration measurement apparatus (100) brings at least a counter electrode (4) and a working electrode (2) into contact with ozone water, which is a sample solution (S), applies voltage between the counter electrode (4) and the working electrode (2), and measures the current value at that voltage, to thereby calculate the ozone concentration in the ozone water. In the ozone water concentration measurement apparatus (100), the working electrode (2) is a conductive diamond electrode, and the surface area that contacts the ozone water of the working electrode (2) is within the range of 628 to 392,500mum .