A differential-pressure flowmeter that can reduce (eliminate) a difference between the ambient temperature of one pressure sensor and the ambient temperature of another pressure sensor so as to allow for accurate and stable pressure measurement is provided, and a flow-rate controller equipped with such a differential-pressure flowmeter is provided. Provided are a body having a main fluid channel through which a fluid, whose pressure is to be measured, flows, and two pressure sensors held by the body and arranged in series relative to the main fluid channel, and a temperature balancer composed of a material with high thermal conductivity is accommodated in a recess that is formed in the body located below the two pressure sensors.