A few kinds of complexane types of chemically modified chitosan, i.e., monocarboxymethylated chitosan (MCM-chitosan) and IDA- and DTPA-types of chitosan (IDA- and DTPA-chitosan) were synthesized to examine the adsorption of palladium(II), platinum(IV), and iridium(III) from hydrochloric acid solution as well as the elution of palladium and platinum and compared with those by crosslinked copper(II)-complexed chitosan (crosslinked chitosan). The adsorption of palladium(II) monotonously decreased with increasing hydrochloric acid concentration with all kinds of adsorbents. The adsorption of platinum(IV) also decreased with increasing hydrochloric acid concentration with all kinds of adsorbents except for DTPA-chitosan, with which it decreased in the low concentration region and increased in the high concentration region. The adsorption of iridium(III) also decreased with increasing concentration of hydrochloric acid with all kinds of adsorbents except for IDA-chitosan, but that on DTPA-chitosan was much smaller than other adsorbents. The adsorption on IDA-chitosan increased with increasing hydrochloric acid concentration in its low concentration region, and decreased in the high concentration region, different from other adsorbents. The magnitude of adsorption capacity of each adsorbent for palladium(II) was in the order MCM-chitosan = IDA-chitosan > DTPA-chitosan > crosslinked chitosan, while that for platinum(IV) was in the order, DTPA-chitosan > MCM-chitosan = IDA-chitosan > crosslinked chitosan. The elution of loaded palladium(II)) and platinum(IV)) with hydrochloric acid solution was much improved by chemical modification, especially that of platinum(IV) which was drastically improved by using IDA- and MCM-chitosan.