To provide an iron wheel falling prevention device for a road/track working vehicle capable of fixing/retaining an iron wheel retaining bracket for retaining the track traveling wheel to a storage position by a relatively simple structure.

The iron wheel falling prevention device for the road/track working vehicle includes a stopper 50 provided on the iron wheel retaining bracket 14 for retaining at least the iron wheel 15b at a rear side of the iron wheels 15 provided at front and rear sides of a vehicle body 2; and a lock pin 43 vertically pivotably provided on the vehicle body 2 and engaged with the stopper 50 when the iron wheel retaining bracket is positioned at the storage position. When the iron wheel retaining bracket 14 is pivoted to the storage position by a pivoting cylinder 16, the lock pin 43 is pushed from the stopper 50 and is pivoted so as to be engaged with the stopper 50. When the iron wheel retaining bracket 14 is pivoted to a projection position by the pivoting cylinder 16, the lock pin 43 is pivoted by a rod pin 55 so as to release the engagement with the stopper 50. Thereby, the stopper 50 is constituted engageably/releasably with the lock pin 43.