A battery pack, comprising: a plurality of battery cells that each include an electrode terminal (22A, 22B); a connection member (15; 15A, 15B); a conductive member (14; 14A, 14B) that includes: a first terminal of a plate shape, connected to the connection member, a second terminal of a plate shape, connected to the electrode terminal, and a bridge located between the first terminal and the second terminal and is fused by heat including self-generated heat; and a heat transfer part that is located in a first part of the conductive member from the bridge to the first terminal, characterized in that the heat transfer part transfers heat so that a first end becomes higher in temperature than a second end in the bridge, the first end being a lateral end of the bridge, the second end being opposite the first end, wherein the conductive member (14; 14A, 14B) includes a fusion part that extends across the first end and the second end, and that is fused by heat including self-generated heat; wherein the heat transfer part includes an asymmetrical part that is included in the first part being from the first terminal to the bridge of the conductive member, and that has an asymmetrical shape with respect to a plane which passes a lateral center of the fusion part and is orthogonal to the lateral direction, and the first terminal is placed closer to the first end than to the second end, whereby the first end of the fusion part reaches a certain temperature earlier than the second end and becomes a fusion start position and the fusing direction of the fusion part is from the end to the end, and the asymmetrical part includes the first terminal and wherein the first terminal has an asymmetrical shape with respect to a plane. a plurality of battery cells that each include an electrode terminal (22A, 22B); a connection member (15; 15A, 15B); a conductive member (14; 14A, 14B) that includes: a first terminal of a plate shape, connected to the connection member, a second terminal of a plate shape, connected to the electrode terminal, and a bridge located between the first terminal and the second terminal and is fused by heat including self-generated heat; and a first terminal of a plate shape, connected to the connection member, a second terminal of a plate shape, connected to the electrode terminal, and a bridge located between the first terminal and the second terminal and is fused by heat including self-generated heat; and a heat transfer part that is located in a first part of the conductive member from the bridge to the first terminal, characterized in that the heat transfer part transfers heat so that a first end becomes higher in temperature than a second end in the bridge, the first end being a lateral end of the bridge, the second end being opposite the first end, wherein the conductive member (14; 14A, 14B) includes a fusion part that extends across the first end and the second end, and that is fused by heat including self-generated heat; wherein the heat transfer part includes an asymmetrical part that is included in the first part being from the first terminal to the bridge of the conductive member, and that has an asymmetrical shape with respect to a plane which passes a lateral center of the fusion part and is orthogonal to the lateral direction, and the first terminal is placed closer to the first end than to the second end, whereby the first end of the fusion part reaches a certain temperature earlier than the second end and becomes a fusion start position and the fusing direction of the fusion part is from the end to the end, and the asymmetrical part includes the first terminal and wherein the first terminal has an asymmetrical shape with respect to a plane.