A washing machine which performs a washing operation by heating water, a detergent, or a wash liquid using a dielectric heating method and a method of controlling the washing machine. The washing machine may include a water supply portion which supplies a wash liquid including water and a detergent, a power supply portion which supplies alternating current (AC) power, and an electric field forming portion which forms an electric field between a first electrode portion and a second electrode portion according to the AC power to heat the supplied wash liquid.