A vehicle speed calculating device includes a vehicle speed calculating unit configured to calculate a control vehicle speed that is acquired by estimating a vehicle body speed that is a speed at which a vehicle is actually traveling, as a state variable used to control an onboard device configured to operate to realize various functions provided in the vehicle. The vehicle speed calculating unit is configured to include an extraction function of extracting at least one wheel speed acquired from at least one wheel that is assumed to be rotating in a state in which an influence causing a difference from the vehicle body speed is likely to be small, out of wheel speeds of a plurality of wheels, and a calculation function of calculating the control vehicle speed based on the at least one wheel speed extracted by the extraction function.