a deflection yoke has magentic field correcting auxiliary yokes disposed at the flare side end of the insulative bobbin for holding a pair of horizontal deflection coils and a pair of vertical deflection coils , each magnetic field correcting auxiliary yokes comprising a long and slender arc shaped core disposed along the end portion of either of the horizontal deflection coils or the vertical deflection coils and a pair of auxiliary coils which are wound on the core and connected in series to the vertical deflection coils ; and thereby the raster distortion and mis - convergence are substantially reduced .