Abstract: A directly-heated cathode structure for use in a compact cathode ray tube comprises an insulating support body, a pair of cathode lead pins fixedly carried in the insulating support body, and a filament extending between the leading ends of said cathode lead pins. An electron emitting material is applied to and coated on the filament over its entire length including its two ends joining with the leading ends of the cathode lead pins so that the electron emitting material once hardened ensures that the two ends of the filament are firmly fixed to the leading ends of the cathode lead pins. The insulating support body may have a groove which is formed across the upper face thereof and within which the leading ends of the cathode lead pins are exposed in a spaced relation, which helps confining undesirable scattering of the electron emitting material when sprayed to the filament.