Each of a plurality of driver ICs, which drives an associated print head, includes an analog voltage provider, which provides an analog voltage which is inversely proportional to a temperature of the driver IC, a reference temperature provider, which provides a digital value corresponding to a reference temperature, a D / A converter, which converts the digital value into a corresponding analog value, and a comparator, which compares the analog voltage with the analog value and outputs a comparison signal indicating whether the analog voltage is higher than the analog value. A temperature detector determines whether the temperature of at least one of print heads is higher than the reference temperature in accordance with the comparison signal.