Volatile organic compounds (VOCs) gas sensor based on gated lateral bipolar junction transistor (LBJT) was developed in this study. The device was fabricated using 0.35-μm logic process by Magnachip-Hynix Co. Ltd. under the Integrated Circuit Design education Center Multi Project Wafer (IDEC-MPW) program. Solvatochromic dye as the sensing membrane was coated on the floating gate of the device. A semiconductor test and analyzer (STA-EL421, ELECS) was used to measure the sensing results. Following the results, we found that the sensing device which used the gated LBJT device has fast responsibility and reversibility to VOC gases (acetone etc.).