A shift control system includes an engine speed detector, a multistage transmission, a gear position detector, a shifting operation detector, and an output controller. The engine speed detector is configured to detect an engine speed. The gear position detector is configured to detect a transmission gear. The shifting operation detector is configured to detect an operation of a shift operating element. The output controller is configured to restrict output of an engine in a case where an up-shifting operation is detected by the shifting operation detector. The output controller is configured to release output restriction of the engine before the gear position detector detects that switching to a next-stage transmission gear by the up-shifting operation of the shift operating element is completed.