Abstract: Disclosed is a crack detection apparatus for detecting a building structure, belonging to the technical field of building detection and including a main shaft collar, an auxiliary shaft collar, a rotating drum, a bracket assembly, a crawling mechanism and a transmission assembly, where the main shaft collar is rotationally connected with the auxiliary shaft collar, main slewing arms and auxiliary slewing arms that are in X-shaped crossing are arranged on the main shaft collar and the auxiliary shaft collar, the rotating drum swinging back and forth is rotationally assembled on the main shaft collar, a tail end of the rotating drum is provided with a cleaning arm, the crawling mechanism is assembled at tail ends of the main slewing arms and the auxiliary slewing arms and connected with the rotating drum through the transmission assembly.