Columnar liquid crystals of discotics have been drawing much attention as novel organic semiconductors due to the fast charge migration phenomena along a columnar axis in the recent decade. And, thus, the applications as one-dimensional conductors, photoconductors, molecular wires and fibers, light emitting diodes and photovoltaic cells have also been exploited. Recent studies of columnar liquid crystal semiconductors indicate the electronic transport in columnar mesophase could strongly depend on the dimension of columnar order. In addition, the ambipolar charge carrier transport is another important property as the organic semiconductors. In this study, ambipolar charge carrier transport properties were investigated for a homologous series of triphenylene (CnOTP; n=4-8, alkyl chain length) by time-of-flight (TOF) method for the homeotropic domains. Temperature dependence of positive and negative charge carrier mobilities were also obtained for Col_hp, Col_ho and Col_hd mesophases dependent on the alkyl chain length. (Figure 1) Ambipolar electronic charge carrier transport was observed and the both positive and negative charge carrier mobilities decrease with the increase of the alkyl chain length. Ionic conduction was also observed for the negative charge carrier transport except for C4OTP and any remarkable dependency of the alkyl chain length was not seen. According to the XRD measurements, C4OTP and C5OTP have a high intracolumnar order in the vicinity of 3.5 Å, in contrast to the undetectable intracolumnar order of the longer homologues. It was reasonably found that both the positive and negative charged carrier mobilities by electronic hopping process is affected by the intracolumnar order in the same manner. In this work, ambipolar charge carrier transport was found for the hexaalkoxy triphenylene homologous in the Col_h and Col_hp mesophases. The temperature dependence of charge carrier mobilities are also reported.