Folding utility knife

A utility knife comprising a handle and a blade holder, said blade holder being pivotally mounted on said handle for movement from an unfolded position to a folded position, said blade holder comprising a main wall structure and a guard wall structure mounted together, said wall structures being adapted to receive a blade therebetween, said blade being removable from between said wall structures when in its inoperative position and being mounted between said wall structure when in its operative position, a blade lock on said blade hold to hold said blade between said wall structures, said blade lock comprising a blade lock lever being pivotally moveable on said blade holder in a direction substantially perpendicular to the said wall structures, said wall structures being mounted together and having a slit therebetween adapted to receive the blade, said blade being substantially stationary and immovable lengthwise relative to said wall structures, when said blade is in its operative position and said blade lock lever being located wholly within the confines of the wall structure at all times.