A monitoring apparatus is provided for monitoring voltages of a plurality of battery cells. The battery cells are electrically connected in series with each other and each include a pair of electrode terminals. The monitoring apparatus includes a flexible substrate, a monitoring circuit and a plurality of noise removal elements. The flexible substrate has a plurality of wiring patterns formed thereon. The wiring patterns are electrically connected with the electrode terminals of the battery cells. The monitoring circuit is electrically connected with the electrode terminals of the battery cells via the wiring patterns and configured to monitor the voltages of the battery cells inputted thereto via the wiring patterns. The noise removal elements are provided in monitoring circuit-side parts of the wiring patterns to remove noise inputted to the wiring patterns.