A method for manufacturing a packing material includes a first step of reacting an inorganic particle having a hydroxyl group with a silane coupling agent including a silane coupling agent having an alkenyl group with a carbon number of 2 or more and 8 or less and/or an alkynyl group with a carbon number of 2 or more and 7 or less and a second step of reacting the inorganic particle having reacted with the silane coupling agent, with a compound represented by a general formula of: (in the formula, R1 is an alkyl group with a carbon number of 4 or more and 50 or less or an aryl group with a carbon number of 6 or more and 30 or less and each of R2 and R3 is independently a hydrogen atom, a chloro group, or an alkyl group with a carbon number of 1 or more and 4 or less.).