The helical guide apparatus includes a main spindle, a male pattern, a first female pattern and a second female pattern which are operatively associated with one another. As the main spindle adapted to reciprocably move in the axial direction and rotate in the circumferential direction is reciprocably driven in the axial direction by first reciprocable driving means, it carries out reciprocable rotational movement in accordance with a lead which is determined by a combination of the first helical projection on the male pattern and the first helical recess on the first female pattern. Then, the first female pattern is caused to carry out reciprocable movement in the axial direction of the main spindle in synchronization with reciprocable movement of the main spindle with the aid of second reciprocable driving means whereby it carries out reciprocable rotational movement in accordance with a lead which is determined by a combination of the second helical projection on the first female pattern and the second helical recess on the second female pattern. Reciprocable rotational movement of the first female pattern is combined with reciprocable rotational movement caused by reciprocable movement of the main spindle. Any required helical angle can be steplessly determined prior to gear cutting operation.