The utility model provides a tunnel monitoring device, include: the sound sensor sets up in the tunnel for the sound sound signal's in the tunnel frequency and/or intensity are spreaded into into in the detection, the treater is connected with the sound sensor for acquire the sound sound signal's that the sound sensor detected frequency and/or intensity, and with the sound sound signal's that prestores in sound sound signal's frequency and the treater frequency ratio, the sound sound signal's that acquires according to the comparative result sureness kind, and/or with the sound sound signal's that prestores in sound sound signal's intensity and the treater intensity ratio to send sound signal's sound source and the distance between the sound sensor according to the comparative result sureness, use the utility model discloses technical scheme's tunnel monitoring device can discover the destruction that the outside construction machinery in tunnel caused tunnel structure in advance when the construction, make maintainer in time deal with, removes a hidden danger, guarantees the normal clear of power supply.