Ultraviolet lamp and ultraviolet irradiating device

An ultraviolet lamp includes a tubular discharge tube, characterized in a curved surface part and a planar part for transmitting ultraviolet on the outer wall of the discharge tube in opposite position. In addition, a surface of the curved surface part inside the discharge tube is a concave. A first electrode is installed on the curved surface part. A second electrode which is line-shaped is installed on the outside of the discharge tube in a manner extending along the lengthwise direction of the discharge tube. The second electrode is located near the central of the planar part. A discharge occurs between the first electrode and the second electrode. There is no other electrode installed on the planner part except the second electrode.