Simultaneous recordings of neural activity at large scale, in the long term and under bio-safety conditions, can provide essential data. These data can be used to advance the technology for brain-machine interfaces in clinical applications, and to understand brain function. For this purpose, we present a new multichannel neural recording system that can record up to 4096-channel (ch) electrocorticogram data by multiple connections of customized application-specific integrated circuits (ASICs). The ASIC includes 64-ch low-noise amplifiers, analog time-division multiplexers, and 12-bit successive approximation register ADCs. Recorded data sampled at a rate of 1 kS/s are multiplexed with time division via an integrated multiplex board, and in total 51.2 Mbps of raw data for 4096 ch are generated. This system has an ultra-wideband (UWB) wireless unit for transmitting the recorded neural signals. The ASICs, multiplex boards, and UWB transmitter unit are designed with the aim of implanting them. From preliminary experiments with a human body-equivalent liquid phantom, we confirmed 4096-ch UWB wireless data transmission at 128 Mbps for distances below 20 mm .