Textile-based sensors have many advantages when applied to body assessment. They have greater comfort than IT sensors and their use has substantially increased recently. Fiber-based sensors have various factors affecting their detecting ability such as pressure, voltage, current, and capacitance. Fiber-based sensor fabrics with sheath-core type conductive yarns were produced and relationships between capacitance changes and applied loads were investigated. The physical and electrical properties of the fiber-based sensor fabrics were investigated under various dyeing and finishing conditions. Dyeing and finishing conditions were optimized with respect to electrical properties using a signal detecting circuit.