Disclosed is a deflection yoke mounted around a glass bulb of a CRT so as to cover a predetermined area of the glass bulb. The predetermined area is where an outer shape of the glass bulb smoothly goes from circular to substantially rectangular along a tube axis of the CRT. The deflection yoke includes a horizontal deflection coil disposed in a shape to fit with the outer shape of the glass bulb, and a funnel-shaped ferrite core disposed to surround the horizontal deflection coil. The inner shape of the ferrite core is circular throughout a length of the ferrite core.