a first cylindrical electrochemical cell having a first electrode facing a first direction;

a second cylindrical electrochemical cell having a second electrode facing the first direction and being adjacent to the first cylindrical electrochemical cell in a second direction perpendicular to the first direction;

a lead wire having a core wire covered by covering material and having one end connected to the first electrode;

a metal plate connected to the second electrode; and

an electrical element provided adjacent to the second cylindrical electrochemical cell and having an axial lead that extends on a first principal surface of the metal plate, the first direction being perpendicular to the first principal surface,

wherein the axial lead includes:

a main body part having a first diameter, and

a connection part that is located from the main body part to an end part of the axial lead and that is connected to the first principal surface,

wherein the connection part includes a first part which is located adjacent to the main body part, which includes a weld part welded to the first principal surface, and which has a first thickness less than the first diameter in the first direction perpendicular to the first principal surface,

wherein the connection part includes a second part, which is located from the first part to the end part, which includes a non-weld part not welded to the first principal surface, and which has a second thickness equal to or less than the first thickness in the first direction, and

wherein the lead wire extends from the one end connected to the first electrode toward the metal plate connected to the second electrode.