A portable device for measuring gas in a closed space includes an air intake and exhaust unit configured to suction external air and discharge the suctioned air, a sensor unit configured to measure characteristics of the air suctioned by the air intake and exhaust unit, a communication unit configured to communicate with a host system, a power supply unit configured to supply power to the air intake and exhaust unit, the sensor unit, and the communication unit, and a control unit configured to control the air intake and exhaust unit, the sensor unit, the communication unit, and the power supply unit so that the sensor unit measures the characteristics of the air suctioned by the air intake and exhaust unit and configured to transmit measurement information to the host system through the communication unit.