This study was conducted to develop a moisture sensor for rapeseed, a bio-diesel material. A typical rapeseed, SUNMANG, was used as a raw material. The rapeseed moisture content sensor consists of three components, such as upper and bottom electrodes, a test material dish, and a fixing housing. To evaluate the performance, a data acquisition system was equipped with the rapeseed moisture sensor, computer, printer, and main board. The findings of this study were: 1) the rapeseed moisture content was inversely proportional to electric resistance, and 2) values of electric resistance were recorded in a range of $10{sim}100;M{Omega}$, depending upon a change of the moisture content. The determination of coefficient ($R^2$) and standard error between rapeseed moisture content and electric resistance were 0.9921 and ${pm}0.289$, which indicated a highly correlative relationship. The response of rapeseed moisture sensor to temperature change was also observed for further performance test. Satisfying results were obtained, such as the determination of coefficient ($R^2$) of 0.9918, predicted standard error of ${pm}0.373%$, deviation of 0.103%, measurement error of $0.14{sim}0.48%$, standard deviation of $0.01{sim}0.22%$, and measurement time of 28.3 s per point, respectively.