A caterpillar device is disclosed. The caterpillar device of the present invention comprises: a water layer removal part provided at a power transmission member including chains, so as to press, by means of the force of a magnet, a water layer between a subject being attached, which is a magnetic substance, and the power transmission member, thereby removing the same and attaching the power transmission member to the subject being attached; and an equipment body magnet attachment part connected to the power transmission member and attaching an equipment body to the subject being attached, which is a ferromagnetic substance, by means of the force of the magnet.