Twenty three samples of man-made mineral fibers (MMMF) were collected and analyzed for their mineral contents using a transmission electron microscope equipped with energy dispersive X-ray analyzer (TEM-EDX). Five glass fibers showed a straight fiber type without branches with average diameter ranged from 2.6㎛ to 5.6㎛ and average length 12.2～29.6㎛. The major atomic compositions of the glass fibers were Na, Mg, Si, Ca, and Fe with a little variance among them and contained trace amounts of Al and Si. Eleven rock wool fibers also showed a straight fiber type without branches. The rock wool fibers used in 3 insulation panel and 1 insulation tube had average diameter 13.6～26.4㎛ and average length 13.6～26.4㎛. The major atomic compositions of the rock wool fibers were Na, Mg, Al, Si, S, Ca, Fe, and Cu with a little variance among them. Two of rock wool sealant fibers and one of coating material fibers had average 0.8～2.2㎛ diameter and 9.9～16.2㎛ average length. The major atomic compositions of the fibers were Mg, Al, Si, Ca, and Fe with a little variance among them and contained trace amount of S. The fibers in the rock wool coating materials contaminated partially with another type of fibers. Four of rock wool ceiling board showed 0.9～2.04㎛ average diameter and 4.3～15.2㎛ average length. The major atomic compositions of the fibers were Mg, Al, Si, S, Ca, and Fe with a little variance among them and contained trace amounts of Na, K, and Ti. Three of long glass fibers showed a mass appearance with finely splitted fibers, and the major atomic compositions of the fibers were Na, Mg, Al, Si, S, Ca, and Fe with no variance among them. One type of ceramic fiber showed 2.9±1.59㎛ average diameter and 20.3±9.38㎛ average length. The major compositions of the fibers were Al, Si, and S. A gypsum board and a perlite and a calcium silicate insulation material all showed aspect ratio less than 3:1, indicating non-fibrous materials. The major compositions of the gypsum board particles were Al, Si, S, K, Ca, and Fe, The perlite particles were consisted of Na, Al, Si, S, K, Ca, and Fe, and the calcium silicate insulation materials were mainly consisted of Al, Si, Ca, and Fe. Keywords：Asbestos substitutes, Man-made mineral fibers, Glass fibers, Rock wool, TEM-EDX