An energy storage device comprising: an electrode assembly formed by winding a positive electrode sheet, a negative electrode sheet and a separator about a winding axis, wherein an end portion of the electrode assembly as viewed in a first direction that the winding axis extends is formed into an elongated circular shape having first and second straight line portions (20c, 20d) which opposedly face each other, and a pair of curved portions which opposedly face each other so as to connect the first and second straight line portions (20c, 20d), and having current collecting tabs (28, 29) which projects from the first straight line portion of the electrode assembly, the electrode assembly being housed in a case; external terminals (50A, 50B) disposed on the case; and current collectors (60A, 60B) disposed between the electrode assembly and the case, electrically connected to the respective external terminals (50A, 50B), and electrically connected to the respective current collecting tabs (28, 29) at respective connecting portions (61A, 61B), wherein the each current collector (60A, 60B) has a upper surface opposed to the case and a lower surface opposed to the electrode assembly, wherein the current collecting tabs (28, 29) are in direct contact with the respective lower surfaces of the respective current collectors (60A, 60B); wherein the current collecting tabs (28, 29) comprise a positive electrode current collecting tab and a negative electrode current collecting tab, the current collectors (60A, 60B) comprise a positive electrode current collector and a negative electrode current collector, and the positive electrode current collecting tab and the negative electrode current collecting tab are disposed on the first straight line portion in a spaced-apart manner in a second direction that the first straight line portion extends, and the respective current collecting tabs (28, 29) and the respective current collectors (60A, 60B) are directly connected to each other only above the second straight line portion when viewed in the second direction. an electrode assembly formed by winding a positive electrode sheet, a negative electrode sheet and a separator about a winding axis, wherein an end portion of the electrode assembly as viewed in a first direction that the winding axis extends is formed into an elongated circular shape having first and second straight line portions (20c, 20d) which opposedly face each other, and a pair of curved portions which opposedly face each other so as to connect the first and second straight line portions (20c, 20d), and having current collecting tabs (28, 29) which projects from the first straight line portion of the electrode assembly, the electrode assembly being housed in a case; external terminals (50A, 50B) disposed on the case; and current collectors (60A, 60B) disposed between the electrode assembly and the case, electrically connected to the respective external terminals (50A, 50B), and electrically connected to the respective current collecting tabs (28, 29) at respective connecting portions (61A, 61B), wherein the each current collector (60A, 60B) has a upper surface opposed to the case and a lower surface opposed to the electrode assembly, wherein the current collecting tabs (28, 29) are in direct contact with the respective lower surfaces of the respective current collectors (60A, 60B); wherein the current collecting tabs (28, 29) comprise a positive electrode current collecting tab and a negative electrode current collecting tab, the current collectors (60A, 60B) comprise a positive electrode current collector and a negative electrode current collector, and the positive electrode current collecting tab and the negative electrode current collecting tab are disposed on the first straight line portion in a spaced-apart manner in a second direction that the first straight line portion extends, and the respective current collecting tabs (28, 29) and the respective current collectors (60A, 60B) are directly connected to each other only above the second straight line portion when viewed in the second direction.