To provide a mobile nitrogen gas producing apparatus which allows for saving time and labor hour in transportation and location arrangement.

A mobile nitrogen gas producing apparatus comprises a first trailer 2 and a nitrogen gas separation tower 1 for low temperature liquefaction and separation type nitrogen gas producing apparatus mounted in a laid state on the first trailer 2. A rear member of the first trailer 2 and adjacent portion of a disposition member of the nitrogen gas separation tower 1 are pivotally connected by a hinge axle 7 which allows the nitrogen gas separation tower to be erected by pivoting the nitrogen gas separation tower via the hinge axle 7.