A height adjustment device for a rotunda can comprise: an outer column which fixes a rotunda and ascends and descends; an inner column which is connected to the outer column; a vertical screw which is placed on the lower end of the rotunda; a nut which is interlocked in correspondence to the outside diameter of the vertical screw; and rails which are provided on one side of the outer column or the inner column and are formed in correspondence to each other so as to assist the ascent and descent of the outer column.