The invention relates to the field of hollowing detection, and especially relates to a hollowing detection device for building construction. The device comprises a guide rail assembly, a driving assembly, a detection assembly and a detection hammer assembly. Through the guide rail assembly and the driving assembly, a servo motor in the driving assembly can drive a lead screw to rotate, the lead screw can drive a first sliding block to slide in a first sliding groove when rotating, and the first sliding block can drive the detection assembly to move along a guide rail when sliding, so the problem that the detection efficiency is reduced due to fatigue generated during manual detection can be effectively avoided; a servo motor in the driving assembly drives the detection assembly to move, a gear can be driven to move along a spur rack, the gear can rotate when moving along the spur rack, the gear can drive a rotating shaft to rotate when rotating, the rotating shaft can drive the shifting block to drive the detection hammers when rotating, and the multiple sets of detection hammers are arranged, so that the area for simultaneous detection of the device is greatly enlarged.