To provide a locking apparatus which can surely maintain a locked state in spite of its relatively low cost, and which is extremely safe in terms of crime prevention.

This locking apparatus comprises a door key (10a) with a latch (12), and an unlocking device (20) which is arranged at a predetermined interval from the door key. The unlocking device (20) comprises a piston cylinder unit (26), a switching valve (28) for supplying/discharging a working fluid to/from the piston cylinder unit, and a receiver (30) for switching the switching valve; and these are provided inside a surface material (2). Thus, the receiver (30) catches a signal which is transmitted from the outside, the switching valve (28) is switched so that the latch (12) can recede by the activation of the unit (26) so as to release the locked state.