Provided is a velocity calculating device including a vertical acceleration detector that detects a vertical acceleration generated due to an undulation of a contact surface; a horizontal angular velocity detector that detects a horizontal angular velocity generated due to the undulation; a correlation coefficient calculator that calculates a correlation coefficient that represents a degree to which an acceleration in the direction of travel is mixed into the vertical acceleration in accordance with an attachment angle; a true vertical acceleration detector that calculates a true vertical acceleration by subtracting the acceleration in the direction of travel mixed into the vertical acceleration from the vertical acceleration, the acceleration in the direction of travel mixed into the vertical acceleration being calculated using the correlation coefficient; and a velocity calculator that calculates a velocity of a moving body on the basis of the true vertical acceleration and the horizontal angular velocity.