This paper presents a rectifier with comparator using unbalanced body biasing in $0.11{mu}m$ RF CMOS process. It is composed of MOSFETs and two comparators. The comparator is used to reduce reverse leakage current which occurs when the load voltage is higher than input voltage. For the comparator, unbalanced body biasing is devised. By using unbalanced body biasing, reference voltage for comparator changing from high state to low state is increased, and it reduces time interval for leakage current to flow. 13.56 MHz 2 Vpp signal is used for input and $1k{Omega}$ resistor and 1 nF capacitor are used for output load for simulation and experimental environment. In simulation environment, voltage conversion efficiency(VCE) is 87.5 % and Power conversion efficiency(PCE) is 50 %. When the rectifier is measured, VCE shows 90.203 % and PCE shows 45 %.