We assessed a quartz pressure sensor characteristics assuming an ocean bottom and borehole environment in the laboratory. Accuracy evaluations of the hydraulic pressure sensors with a scale of 1 hPa are required for obtaining small pressure change related to crustal deformations on the seafloor. However, quantitative assessments to understand pressure sensor characteristics are not performed yet. We performed 4 patterns of experiments to understand characteristics. A pressure hysteresis width was 3.21 and 1.56 hPa for the applied pressure width of 10 to 30 MPa and 15 to 25 MPa, respectively. The temperature characteristics of the sensor are 3.12 hPa/degC. The temperature hysteresis of the sensor is 1.12 hPa when the outside environment of the pressure sensor is 3.0 degC. The tilt characteristics of the pressure sensor is 0.42 hPa/degC. These characteristics of the quartz pressure sensor would influence on detection of small amount of crustal deformation on the seafloor.