A fluid treatment apparatus capable of maximizing contact area between a fluid and electrodes in the apparatus to improve corrosion resistance or combustion efficiency includes a housing having an inlet port and an outlet port for the water at both ends of the housing, and a plurality of first electrodes installed in the housing for generating a potential difference through delivery of electrons at a contact surface between the fluid and the electrodes. The first electrodes are disc shaped and have a water passing hole formed in a center portion. The first electrodes being arranged in parallel in a direction perpendicular to a main flow direction of the fluid, so as to form a channel between the first electrodes to branch and guide a main flow.