An electrode connection cause determination system includes a position measuring instrument. The position measuring instrument is configured to, when an electrode moves between an unwinder and a rewinder in a roll-to-roll state, acquire coordinate value data based on a longitudinal position of the electrode determined according to a rotation amount of the rewinder. The system includes a signal generator configured to generate a connection advance notice signal if the electrode includes a connecting portion corresponding to a cause event, a seam detector configured to detect a seam attached onto the electrode after the connection advance notice signal is generated, and a determination unit configured to, when the seam is detected within a predetermined distance from a first coordinate value of the electrode after the connection advance notice signal is generated, determine that a connection cause of an electrode connection by the seam corresponds to the cause event.