A tap tool holder for a tap tool is disclosed. The tap tool has a cylindrical body and a tap extended from the cylindrical body. The tap tool holder includes a bracket sleeve for inserting the tap and a positioning collar. An annular inner step is formed in one end of the bracket sleeve. The positioning collar is carried on the annular inner step. The positioning collar has an outer ring wall, and the outer ring wall is attached to the annular inner step. The positioning collar has an inner ring wall, and a shape of the inner ring wall corresponds to an outer side wall of the cylindrical body so as to sleeve the cylindrical body. With the positioning collar that can be replaced corresponding to tap tools, tap tools of various sizes can be positioned in the bracket sleeve to facilitate tapping.