A portable air compressor (compressor) used in a power tool or the like is a known example of the electric tool.  Also, an impact driver is also known as an example of the electric tool for use in fastening screws, bolts, and so on.  Also, a portable cutter (circular saw) is known as an example of the electric tool for cutting a workpiece with disc-shaped blades by rotating the blades.  Also, a desktop cutter (desktop circular saw) is known as an example of the electric tool for cutting a workpiece mounted on a base portion with disc-shaped blades by rotating the blades. 
Such portable electric tools are brought into a construction site and the like and used, in relatively many cases.  However, the electric tools may be left in the site during break time such as lunch, or after the work of the day, in some cases, resulting in a case in which the electric tool may be stolen.  Accordingly, it is desired to improve the security of the electric tools. 
Note that an air compressor including a compressed air generation unit driven by a motor is disclosed in, for example, Patent Document 1.