The paper presents a new method and design of a capacitive sensor for measuring the mass fraction of water in agricultural and dispersed materials. The principles of operation of the proposed measuring instrument, its structural features, and improved metrological characteristics are described. A detailed analysis of various factors affecting measurement accuracy is conducted, and the results of experimental studies confirming the effectiveness of the developed device are presented. The proposed measuring device consists of a housing, a cover, capacitive electrodes, a measuring resonant circuit, inductive and capacitive elements, an AC voltage source, and an indicator device. The two adjacent inductive arms of the ferroresonant bridge circuit consist of two series-connected coils wound on a common toroidal core. The output of the bridge circuit is connected to a threshold voltage indicator, while the input is connected to the AC power network (50 Hz) through an autotransformer. The transformer’s slider is mechanically linked to an arc-shaped scale graduated in units of moisture content for food and bulk materials. Experimental results confirm the sensor’s high accuracy and stability, making it a promising solution for applications in agriculture, the food industry, and other sectors.