A method for purifying a nonaqueous liquid substance includes: filling a cartridge container with a macroporous or porous type ion exchange resin in a water-wet state to obtain an ion exchange resin-filled cartridge filled with the macroporous or porous type ion exchange resin before water content reduction; reducing a water content of the macroporous or porous type ion exchange resin in the cartridge container until a water content (A) of the macroporous or porous type ion exchange resin after water content reduction becomes 90 to 97% of a water content (B) of the macroporous or porous type ion exchange resin in a saturated equilibrium state; an initial blowing step of allowing the nonaqueous liquid substance before being purified to pass inside the cartridge container filled with the macroporous or porous type ion exchange resin after water content reduction and discharging an initial blow effluent from inside the cartridge container; and purification.