An oven including a heater arranged in a cooking compartment, a temperature sensor to sense a temperature of the cooking compartment for a plurality of preset periods of time, and a controller to reset on/offtimes of the heater for at least one of the plurality of preset periods based on a preset target temperature and a current temperature and a previous temperature of the cooking compartment, sensed by the temperature sensor, and to control a driving of the heater according to the reset on/off times. By controlling the on/off times of the heater, a ripple phenomenon which occurs because the target temperature does not remain the same may be decreased. Thus, temperature differences may be reduced during cooking of food and, accordingly, cooking ability may be enhanced.