A prediction system includes an acquisition device, an execution device, and a prediction device. The acquisition device is configured to acquire a value of electric resistance of a cable secured by fixing members to a pair of link members configured to rotate relative to each other through a joint. The execution device is configured to cause the joint to execute a predetermined operation. The prediction device is configured to predict a service life of the cable based on a change in the value of electric resistance acquired by the acquisition device while the execution device is causing the joint to execute the predetermined operation.