A temperature measuring device includes first and second semiconductor elements each of which has a p-n junction, a transistor group including a plurality of transistors of which respective sources are connected to a power source and of which respective gates are connected to each other, the plurality of transistors constituting a current source, the transistor group being configured to output a first current and a second current having a different magnitude from the first current to the first and second semiconductor elements, respectively, and a selector configured to select at least one first transistor and a plurality of second transistors different from the first transistor, from among the plurality of transistors.