An oil filter module comprising: a casing having an open end; a filter installed in the casing and comprising: a pipe-shaped support frame having a plurality of openings in a sidewall thereof; filter paper enclosing an outer surface of the support frame; an upper support plate coupled to the support frame and configured to cover an upper end of the filter paper; and a bottom support plate coupled to the support frame and configured to cover a lower end of the filter paper; a cap threadedly coupled to the casing to cover the open end of the casing, the cap including a drain nipple protruding downward from a portion of the cap corresponding to the bottom support plate, with a drain hole formed in the drain nipple; and a drain pin coupled to the drain nipple so as to be removable so that the drain hole formed in the drain nipple is opened or closed by the drain pin, characterized in that an annular rotation groove having a rotating axis of the casing as a central axis thereof is formed in a lower surface of the bottom support plate, the drain hole is formed at a position corresponding to the rotation groove, and the drain pin is seated at one end thereof onto a bottom of the rotation groove when the drain pin is coupled to the drain nipple, wherein the drain pin comprises: a pin body inserted into the drain hole in a force-fitting manner; a slide block seated on the bottom of the rotation groove and formed on a first longitudinal end of the pin body in a block shape such that the slide block can slide along the rotation groove when the cap is rotated in a direction in which the cap is threadedly rotated. a casing having an open end; a filter installed in the casing and comprising: a pipe-shaped support frame having a plurality of openings in a sidewall thereof; filter paper enclosing an outer surface of the support frame; an upper support plate coupled to the support frame and configured to cover an upper end of the filter paper; and a bottom support plate coupled to the support frame and configured to cover a lower end of the filter paper; a cap threadedly coupled to the casing to cover the open end of the casing, the cap including a drain nipple protruding downward from a portion of the cap corresponding to the bottom support plate, with a drain hole formed in the drain nipple; and a drain pin coupled to the drain nipple so as to be removable so that the drain hole formed in the drain nipple is opened or closed by the drain pin, characterized in that an annular rotation groove having a rotating axis of the casing as a central axis thereof is formed in a lower surface of the bottom support plate, the drain hole is formed at a position corresponding to the rotation groove, and the drain pin is seated at one end thereof onto a bottom of the rotation groove when the drain pin is coupled to the drain nipple, wherein the drain pin comprises: a pin body inserted into the drain hole in a force-fitting manner; a slide block seated on the bottom of the rotation groove and formed on a first longitudinal end of the pin body in a block shape such that the slide block can slide along the rotation groove when the cap is rotated in a direction in which the cap is threadedly rotated. a pin body inserted into the drain hole in a force-fitting manner; a slide block seated on the bottom of the rotation groove and formed on a first longitudinal end of the pin body in a block shape such that the slide block can slide along the rotation groove when the cap is rotated in a direction in which the cap is threadedly rotated.