A semiconductor device includes: a semiconductor substrate; a flow sensor having a first heater for detecting a flow rate of fluid; and a humidity sensor for detecting a humidity of the fluid. The flow sensor and the humidity sensor are disposed on the semiconductor substrate. The flow sensor is disposed around the humidity sensor. The humidity sensor is disposed on an upstream side of the first heater. Since the device includes the humidity sensor, moisture in the fluid is compensated so that detection accuracy of the flow rate is improved.