Abstract: A power focus device in a camera has a manually rotatively operated focus ring, a lens driving drive source for driving a focusing lens, and a pulse generating device operatively associated with the rotation of the focus ring to generate a pulse signal conforming to the amount of rotation of the focus ring. A focus ring rotation direction detecting device detects the direction of rotation of the focus ring from the pulse signal, a focus ring rotation amount detecting device detects the amount of rotation of the focus ring from the pulse signal, and a drive direction setting device sets the direction of drive of the lens driving drive source on the basis of the result of the detection in the focus ring rotation direction detecting device. A drive amount setting device memorizes the result of the detection in the focus ring rotation amount detecting device and sets the memorized value as the amount of drive of the lens driving drive source.