This paper describes a micromachined pressure sensor that senses pressure not by a diaphragm structure but by a resonantly vibrating comb-drive actuator. The electrical admittance of the comb-drive actuator was directly measured using a lock-in amplifier, and its pressure dependence was examined. From the experiment, it was found that the resonant frequency of the comb-drive actuator gradually drops as the pressure increases. The sensitivity of the comb-drive actuator as a pressure sensor was 0.34 Hz/MPa at atmospheric pressure and 0.1 Hz/MPa at 0.4 MPa absolute pressure.