Abstract: A flow rate measuring device comprising a counter for counting pulses from a flow rate detector, a detector for detecting the temperature of a fluid to be measured, a difference detector for calculating the difference between the measured temperature from the temperature detector and a reference temperature, an arithmetic operation unit for executing predetermined arithmetic operations using the counted value from the counter, the temperature difference from the difference detector and the constant based on specific gravity, and a pulse generator for generating pulses based on the signal from the arithmetic operation unit.