We think that the optical disk is more suitable than the videocassette recorders (VCRs) for the recording system because of its fast access time and its suitablity for archiving. An optical disk camera system for Hi-vision (high-definition television) is expected for the above merits. To realize such a system, a high-transfer-rate of more than 100 Mbps per channel is required. We have studied new partial-response most-likelihood (PRML) channel for use with high-transfer-rate optical disk. We measured the transfer function of the optical disk system. We consider that the amplitude characteristic can be modeled by the sinc function and the phase characteristic is almost flat at 0 degree. Using this function, we simulated to evaluate the channels. We chose the run length limited (1,7) (RLL(1,7)) code for the data coding. Then we recorded data on the trial disk and measured the bit-error rate (BER) using the PR(1,1,1)ML channel, by which a low BER was obtained in the simulation. The scale of the PR(1,1,1)ML circuit is so small that we consider it to be suitable for use in the high-transfer-rate optical disk system. In the recording experiment, using the RLL(1,7) coding and PR(1,1,1)ML, a BER of less than 10-5 was achieved.