To obtain a loose detection device capable of detecting a screw loose safely and moreover with excellent workability, without requiring a worker to have a high level of skill or performance.

The loose detection device 1 includes a vibration generation means 7 for transmitting predetermined ultralow-frequency vibration 3 to an object to be inspected 5, a loose spot analysis means 15 for collecting/analyzing data on vibration generated by the object 5 having received the vibration 3 and calculating the distribution of loosened spots, and a display means 17 for displaying an image of the distribution of the loosened spots calculated by the analysis means 15.