We propose an enhanced physical random access channel (PRACH) preamble detector, which efficiently identifies non-orthogonal preambles while suppressing the noise rise. The proposed PRACH preamble detector reconstructs preambles from the received signal and efficiently utilizes them to improve the detection performance. Through simulations, we verify that the proposed detector successfully detects the desired preambles while suppressing the undesired noise rise, and, thus, it can detect ten non-orthogonal preambles simultaneously with an extremely low mis-detection probability lower than $10^{-5}$ , while achieving a false alarm probability of approximately $10^{-3}$ .