A flash device for use in association with a camera is disclosed. The camera provides focal length data representing a focal length of a lens mounted on the camera to the flash device. The flash device comprises a body portion, a flash head pivotally mounted on the body portion, a xenon tube provided in the flash head for emitting a flash light, and a lens is provided in front of the light emitting means movably to change the angle of the cone of the flash light. A driving circuit, controlled by a microcomputer, is provided for driving the lens in response to the focal length data to set the angle of the cone of the flash light correspondingly to the focal length. A pivot detector is provided for detecting the pivotal movement of the flash head. When the pivotal movement is detected, the microcomputer controls the driving circuit so as not to drive the lens but to maintain the lens, during and after the pivotal movement, in the same position as it was before the pivotal movement.