BUCKLE DEVICE

PROBLEM TO BE SOLVED: To provide a buckle device capable of surely detecting whether a tongue plate is locked or not over a long period. SOLUTION: A magnetic plate 84 is integrally adhered to a lock pin holder 56 and a magnet 82 is arranged so as to face the magnetic plate 84 along a sliding direction of the lock pin holder 56. On a lower side of the magnet 82, a magnetic resistance element 86 is arranged adjacent to the magnet 82. When an engagement part 38 of the lock plate 28 enters into an engagement hole 38 and the lock pin holder 56 is moved together with a lock pin 62 according to the entering, the magnetic plate 84 is away from the magnet 82. Therefore, the magnetic field of the magnet 82 attracted to the magnetic plate 84 so far is changed in direction and a resistance value of the magnetic resistance element 86 is changed at this time. As a result, whether the tongue 12 is locked or not can be detected.