Disclosed herein is a technology for fabricating a nanowire field-effect sensor, in which a bulk silicon substrate is used so that the fabrication cost of the sensor can be reduced while the integration density of the sensor can be increased. In addition, the nanowire field-effect sensor includes a nano-network having a network structure in which pins are vertically arranged on the sidewalls of the network, respectively, and a gate insulating layer is applied to the pins. Due to this nano-network, the detection area of the sensor can be increased to increase its sensitivity, and the structural stability of the sensor can be ensured.