The present invention provides a semiconductor device and a measurement method that enables high precision measurement of temperature or humidity or the like over a wide range. A semiconductor device of the present invention determines which is faster out of a reference oscillation and a thermistor oscillation, and using the faster oscillation as a reference, measures a count value based on the other oscillation. Moreover, the count based on the faster oscillation is employed as a reference value, and a count value based on the other oscillation when the reference value is taken as a measurement value. A frequency ratio is computed based on the reference value and the measurement value, and based on the computed frequency ratio, a table expressing correspondence relationships between frequency ratio and temperature is referred to and a temperature acquired.