A safety box for use with an intravenous infusion set is disclosed to include a box body having a locating groove located on each of the front and rear sides thereof for receiving the flexible tube of the intravenous infusion set and a retaining hole located on one lateral side thereof, and a box cover hinged to the box body and having a hook block with two hooked portions selectively engageable into the retaining hole of the box body to temporarily or permanently lock the box cover to the box body.