An image forming system including: a head; a carriage moving mechanism including a carriage, a motor, and a transmission; a motor driver; an encoder; and a controller is provided. The controller is configured to: identify, regarding a certain period being each of the plurality of periods, an index value regarding abnormality of the image forming system based on time series data of a moving velocity, a physical amount related to the moving velocity, or an operation amount observed in a moving control of the carriage in the certain period; and determine an end of a service life of the image forming system or a remaining amount of the service life of the image forming system based on a change of the index value over the plurality of periods.