Disclosed herein is a delay circuit for a low power ring oscillator. The delay circuit includes: a pair of N type transistors that receive first differential input signals Vin1+ and Vin1−; a pair of P type transistors that receive second differential input signals Vin2+ and Vin2−; a differential output terminal that outputs differential output signals Vout+ and Vout− generated from the pair of N type transistors and the pair of P type transistors; an N type detector that supplies a body voltage to the pair of N type transistors; and a P type detector that supplies a body voltage to the pair of P type transistors.