Provided are: an operation assistance method capable of providing a delivery route with a smaller discharge amount for delivery work; an operation assistance system; and an electric vehicle capable of performing deliveries on a delivery route suited to the delivery work. The operation assistance method assists with a delivery by an electric vehicle (2) which has a storage battery (21) and delivers goods. The operation assistance method includes a delivery information acquisition step, a prediction step, a determination step, and a notification step. In the delivery information acquisition step, delivery information including a delivery destination of goods to be delivered is acquired. In the prediction step, a discharge prediction amount which will be discharged by the storage battery (21) in the delivery of the goods is predicted. In the determination step, a delivery route is determined on the basis of the delivery destination of the goods and the discharge prediction amount. In the notification step, a notification of the delivery route is issued.