PCT No. PCT / JP97 / 01748 Sec. 371 Date Jul. 7, 1998 Sec. 102(e) Date Jul. 7, 1998 PCT Filed May 26, 1997 PCT Pub. No. WO98 / 20081 PCT Pub. Date May 14, 1998A carrier particle (A) is
previously treated with a compound (B) such as a
silane coupling agent, if necessary. To the carrier particle, a free functional group is introduced by allowing a reactive group of the carrier particle (A) to react with a compound (C) such as a bisoxazoline compound. As a result, a reactive particle represented by the following formula (I): [C-(B1)m]n-A-[(B2)p-D]q (I) wherein A is a carrier particle, C is an
organic group having at least one free functional group, D is a hydrophilic or hydrophobic group, B1 is an
organic group connecting the carrier particle A to the
organic group C and B2 is an organic group connecting the carrier particle A to the hydrophilic or hydrophobic group; n is an integer of not less than 1, m and p are 0 or 1, q is 0 or an integer of not less than 1, m and p may be different according to n and q; and having a number of active sites can be obtained. A hydrophilic or hydrophobic group may be introduced to the carrier (A).