1. An imaging apparatus comprising: an optical system including a focus lens; an imaging unit operable to capture a subject image formed by the optical system to generate image data; a driver operable to drive the focus lens along an optical axis of the optical system; and an autofocus adjusting unit operable to adjust a subject image formed on the imaging unit to be in focus by evaluating the image data generated by the imaging unit and by controlling the driver to drive the focus lens; and a motion detector for detecting a motion of at least one of the imaging apparatus and the subject, wherein when adjusting the subject image to be in focus anew after previously adjusting the subject image to be in focus, the autofocus adjusting unit controls the driver to drive the focus lens according to a driving method among different driving methods, the driving methods including a driving method for driving the focus lens in one direction when a magnitude of the motion detected by the motion detector is larger than a predetermined value, and a driving method for driving the focus lens in one direction and, after the driving in the one direction, driving the focus lens in a direction opposite to the one direction when the magnitude of the motion detected by the motion detector is smaller than the predetermined value.