For measuring calcium content during the manufacturing process of Tofu, conductometric electrodes were made with the copper plate, and the results were compared with chemical analysis methods. Three types of plate material (Ⅰ, Ⅱ, Ⅲ) for electrode were tested to apply for measuring CaCl₂ content in solution. drained solution from Tofu and in agar-agar gel and Tofu. Empirical linear correlation equations between conductivity (Y, mho) and calcium content (C, Mole; C, ㎎% wet basis) were obtained for the quick estimation of calcium content during Tofu processings. Equations with plate Ⅱ type electrode were Y=0.6364C+0.0775 for drained solution with r=0.99, and Y=7.1503×10^(-5)C-2.9895×10^(-3) for Tofu with r=0.91, respectively.