In a rectangular battery, a lead 9L connected to an electrode plate having a first polarity is connected to a battery case 1 which is an external terminal having the first polarity. A lead 11L connected to an electrode plate having a second polarity is connected to an external terminal 25 having the second polarity, through a connection plate 29. A distance between the battery case 1 and the connection plate 29 at at least one end of the battery case 1 in a long-side direction is equal to or less than the half of the width of the battery case 1 in a short-side direction thereof.