The small current detection circuit is the core component of the accurate detection of the nanopore sensor. In this paper, a compact, low-noise, and high-speed trans-impedance amplifier is built for the nanopore detection system. The amplifier consists of two amplification stages. The first stage performs low-noise trans-impedance amplification by using ADA4530-1, which is a high-performance FET operational amplifier, and a high-ohm feedback resistor of 1 GΩ. The high pass shelf filter in the second stage recovers the higher frequency above the 3 dB cutoff in the first stage to extend the maximum bandwidth up to 50 kHz. The amplifier shows a low noise below sub-2 pA rms when tuned to have a bandwidth of around 5 kHz. It also guarantees a stable frequency response in the nanopore sensor.