A spectrum sensor for cognitive wireless communication which is provided in a cognitive wireless communication system comprising a wireless communication device capable of making cognitive wireless communication and is directed for sensing spectra in multiple frequency bands, wherein the spectrum sensor comprises a controller for controlling an operation mode to switch between a spectrum sensing mode in which the spectra are sensed and a communication mode in which communication is made with the wireless communication device during one symbol period of an ultra-wideband physical layer, characterised in that the spectrum sensor for cognitive wireless communication comprises: a first integrator and a second integrator; a first antenna for receiving an external wireless signal; bandpass filters (B 0, B 1, By, · · ·, B N) provided between the first antenna, and the first integrator and the second integrator; a group of antennas including second antennas for receiving external wireless signals; and a filter bank configured of a plurality of bandpass filters provided between the group of antennas, and the first integrator and the second integrator, wherein the controller switches the operation mode to be a spectrum sensing mode when the spectra are sensed and to be a communication mode when communication is made so that the external wireless signals are input into both the first integrator and the second integrator via the bandpass filters (B 0, B 1, B 2, · · ·, B N) or the filter bank; a code inverter for inverting an output value of the second integrator; a first adder for adding an output value of the first integrator and the output value of the second integrator inverted by the code inverter; a first determination device connected to the first adder in series; a second adder for adding the output value of the first integrator and the output value of the second integration value not inverted by the code inverter; and a second determination device connected to the second adder in series, wherein the controller causes the first determination device to output information by use of the output value of the first adder when the operation mode is the communication mode, and causes the second determination device to output information by use of the output value of the second adder when the operation mode is the spectrum sensing mode. a first integrator and a second integrator; a first antenna for receiving an external wireless signal; bandpass filters (B 0, B 1, By, · · ·, B N) provided between the first antenna, and the first integrator and the second integrator; a group of antennas including second antennas for receiving external wireless signals; and a filter bank configured of a plurality of bandpass filters provided between the group of antennas, and the first integrator and the second integrator, wherein the controller switches the operation mode to be a spectrum sensing mode when the spectra are sensed and to be a communication mode when communication is made so that the external wireless signals are input into both the first integrator and the second integrator via the bandpass filters (B 0, B 1, B 2, · · ·, B N) or the filter bank; a code inverter for inverting an output value of the second integrator; a first adder for adding an output value of the first integrator and the output value of the second integrator inverted by the code inverter; a first determination device connected to the first adder in series; a second adder for adding the output value of the first integrator and the output value of the second integration value not inverted by the code inverter; and a second determination device connected to the second adder in series, wherein the controller causes the first determination device to output information by use of the output value of the first adder when the operation mode is the communication mode, and causes the second determination device to output information by use of the output value of the second adder when the operation mode is the spectrum sensing mode.