A controller that controls travel of a straddle-type vehicle, the controller comprising: a control section capable of executing adaptive cruise control in which the straddle-type vehicle is made to travel according to a distance from said straddle-type vehicle to a preceding vehicle, motion of said straddle-type vehicle, and a driver's instruction, wherein during the adaptive cruise control: when a state where a brake system of the straddle-type vehicle generates a braking force on at least one of wheels (3, 4) of the straddle-type vehicle is switched to a state where a drive wheel is driven using drive power output from a drive source of the straddle-type vehicle, the control section controls the braking force generated on the at least one of the wheels (3, 4) such that a reference braking force is generated on the drive wheel at a time point at which the drive wheel starts being driven due to transmission of the drive power output from the drive source to the drive wheel, the reference braking force is set to a braking force of such extent that can maintain acceleration performance of the straddle-type vehicle to desired performance while alleviating a shock generated at the time point at which the drive wheel starts being driven. a control section capable of executing adaptive cruise control in which the straddle-type vehicle is made to travel according to a distance from said straddle-type vehicle to a preceding vehicle, motion of said straddle-type vehicle, and a driver's instruction, wherein during the adaptive cruise control: when a state where a brake system of the straddle-type vehicle generates a braking force on at least one of wheels (3, 4) of the straddle-type vehicle is switched to a state where a drive wheel is driven using drive power output from a drive source of the straddle-type vehicle, the control section controls the braking force generated on the at least one of the wheels (3, 4) such that a reference braking force is generated on the drive wheel at a time point at which the drive wheel starts being driven due to transmission of the drive power output from the drive source to the drive wheel, the reference braking force is set to a braking force of such extent that can maintain acceleration performance of the straddle-type vehicle to desired performance while alleviating a shock generated at the time point at which the drive wheel starts being driven. when a state where a brake system of the straddle-type vehicle generates a braking force on at least one of wheels (3, 4) of the straddle-type vehicle is switched to a state where a drive wheel is driven using drive power output from a drive source of the straddle-type vehicle, the control section controls the braking force generated on the at least one of the wheels (3, 4) such that a reference braking force is generated on the drive wheel at a time point at which the drive wheel starts being driven due to transmission of the drive power output from the drive source to the drive wheel, the reference braking force is set to a braking force of such extent that can maintain acceleration performance of the straddle-type vehicle to desired performance while alleviating a shock generated at the time point at which the drive wheel starts being driven.