A method of sensing a temperature of a semiconductor device, includes: measuring, by a time measuring circuit, time until a count value, which is obtained from a counter by counting a first signal having a frequency corresponding to a first voltage, reaches a largest count value which can be counted by the counter; and obtaining, by the counter, a piece of digital information corresponding to the first voltage based on a count value obtained by counting a second signal having a frequency corresponding to a second voltage, which is different from the first voltage, based on the time measured by the time measuring circuit, the first voltage depending upon the temperature of the semiconductor device.