In a cruise controller for a saddle-seat vehicle, it is configured to comprise desired throttle opening control execution means (ECU 110) for executing desired throttle opening control by operating the actuator (74) such that the actual throttle opening becomes the desired throttle opening, determine whether the throttle opening command APS is in a predetermined relationship with the actual throttle opening TPS (S60), and switch the cruise control to the desired throttle opening control (S50) when it is discriminated that they are in the predetermined relationship and a disable condition has been established (S62 to S66). By suitably setting the predetermined relationship, the cruise control can be disabled and shifted to the desired throttle opening control at the actual throttle opening anticipatable by the operator, so that driving feel is not impaired and no unnecessary engine output is produced upon switching to the desired throttle opening control.