Control device, control method and computer program for changing a scale of a map

A control device, comprising different units for specifying an operation amount of a user operation; for setting a final control value being the control value after a completed change, based on a pre-change control value that is the control value before the change and the operation amount; and for changing the control value in a stepwise manner from the pre-change control value to the final control value within a prescribed control value range, in a number of stages being based on a difference between the pre-change control value and the final control value, wherein a tentative final control value is specified that is shifted from the pre-change control value by a shift amount that is based on the operation amount, the tentative final control value and a limit value of the control value range are compared, and the limit value or the tentative final control value are set as the final control value.