PURPOSE: To purify gas contg. bromine and/or iodine by allowing the gas to contact with β-cyclodextrine and to include bromine and/or iodine in the gas.

CONSTITUTION: Gas contg. bromine and/or iodine, for example, the gaseous chlorine contg. bromine and iodine produced in soda industry is passed through an absorption apparatus contg. soln. of β-cyclodextrine. Bromine and iodine in the gaseous chlorine are included in the β-cyclodextrine, thus, chlorine is purified. The amt. to be included in the β-cyclodextrine is 1mol bromine or iodine per 1mol β-cyclodextrine. The β-cyclodextrine which has included bromine and/ or iodine is regenerated by the irradiation with supersonic wave or by heating, and is usable repeatedly.