Abstract: A non-reciprocal circuit element for transmitting a high-frequency signal of microwave band in one direction. The electrical characteristics of the non-reciprocal circuit element have been improved by using an insulating sheet having a thickness within a specific range thereby to regulate the distance between vertically adjacent strip electrodes within a specific range. Also, the product-to-product variation in the electrical characteristics of the non-reciprocal circuit element has been minimized by shaping the end portion of the strip electrode so as to extend in coplanar relationship to the top surface of the capacitor to be connected.