Rotationally resolved spectra of the 5s-7s, 5p-7p, 5d, 6d, and 4f-6f Rydberg states (v = 1) of jet cooled CO have been measured by ion-dip spectroscopy with triple resonance excitation via the 3ssigma B 1SIGMA+ (v = 1 ) state. The dip spectra due to the high Rydberg (v = 1) <-- B 1SIGMA+ (v = 1) transition revealed the states most of which have not been observed by other spectroscopy. By the rotational analysis of the dip spectra, electronic term values, quantum defects, and rotational constants were obtained. For the np Rydberg states, the change of the angular momentum coupling between the p Rydberg electron and the CO+ core was clearly observed as a function of the principal quantum number, n, indicating a transition from Hund’s case (b) to Hund’s case (d). It was found that the rotational constant of the nssigma state increases with n, while that of the ndsigma state decreases. The changes in the rotational constants were interpreted by the mixing between the nssigma, state and the (n - 1 ) dsigma state and the mixing coefficients for those states were determined. For the 4f, 5f, and 6f Rydberg states, only the rotational levels belonging to e-symmetry were observed in the dip spectrum. It indicates the selective predissociation through the low lying D’ 1SIGMA+ state.