A battery pack 1 includes a battery 100, a control member (a control board 401) that controls the battery 100, a communication line (an electric wire 405) conducted to the control board 401, a covering member 422 that covers the electric wire 405, and a fastening member 421 that fastens the electric wire 405 with the covering member 422 interposed therebetween. The covering member 422 includes a portion to be fastened 422c surrounded and fastened by the fastening member 421, and a covering portion (a first covering portion 422a) exposed from the fastening member 421. The first covering portion 422a has a portion located on a side closer to the control board 401 than the fastening member 421 and having an outer diameter (D1 > D2) larger than that of the portion to be fastened 422c before being fastened by the fastening member 421.