A gear-shift control data generation method executed by an execution device in a state where relational regulation data used for regulating a relationship between a state of a vehicle and an action variable is stored in a storage device, the action variable being a variable associated with an operation of a transmission mounted on the vehicle, the gear-shift control data generation method comprising: an acquisition process for acquiring the state of the vehicle based on a detection value of a sensor; an operation process for operating the transmission to switch a gear ratio; a reward calculation process for assigning, based on the state of the vehicle acquired by the acquisition process, a higher reward when a characteristic of the vehicle satisfies a criterion than when the characteristic does not satisfy the criterion; and an update process for updating the relational regulation data by inputting, to an update mapping determined in advance, the state of the vehicle acquired by the acquisition process, a value of the action variable used for the operation of the transmission, and a reward corresponding to the operation, wherein: the update mapping outputs the relational regulation data that is updated to increase an expected profit for the reward when the transmission is operated according to the relational regulation data; and characterised in that the criterion when the reward is assigned by the reward calculation process is defined for a combination of values of a first variable and a second variable that are two from among four variables of a gear-shift time required for switching the gear ratio, a heat generation amount of the transmission during a period of switching the gear ratio, an amount in which a rotation speed of an input shaft during the period of switching the gear ratio exceeds a reference rotation speed, and an impact amount generated when switching the gear ratio. an acquisition process for acquiring the state of the vehicle based on a detection value of a sensor; an operation process for operating the transmission to switch a gear ratio; a reward calculation process for assigning, based on the state of the vehicle acquired by the acquisition process, a higher reward when a characteristic of the vehicle satisfies a criterion than when the characteristic does not satisfy the criterion; and an update process for updating the relational regulation data by inputting, to an update mapping determined in advance, the state of the vehicle acquired by the acquisition process, a value of the action variable used for the operation of the transmission, and a reward corresponding to the operation, wherein: the update mapping outputs the relational regulation data that is updated to increase an expected profit for the reward when the transmission is operated according to the relational regulation data; and characterised in that the criterion when the reward is assigned by the reward calculation process is defined for a combination of values of a first variable and a second variable that are two from among four variables of a gear-shift time required for switching the gear ratio, a heat generation amount of the transmission during a period of switching the gear ratio, an amount in which a rotation speed of an input shaft during the period of switching the gear ratio exceeds a reference rotation speed, and an impact amount generated when switching the gear ratio. the update mapping outputs the relational regulation data that is updated to increase an expected profit for the reward when the transmission is operated according to the relational regulation data; and characterised in that the criterion when the reward is assigned by the reward calculation process is defined for a combination of values of a first variable and a second variable that are two from among four variables of a gear-shift time required for switching the gear ratio, a heat generation amount of the transmission during a period of switching the gear ratio, an amount in which a rotation speed of an input shaft during the period of switching the gear ratio exceeds a reference rotation speed, and an impact amount generated when switching the gear ratio.