Species of the pillars in the 4 different buildings(Sudaridjang, Beopbojeon, Dongsaganjang, Seosaganjang) in which Tripitaka Koreana wood blocks are conserved were identified. 1. In 114 pillars, including 6 partially piled-up pillars, 73(64%) was Zelkova serrata, 17(14.9%) was Pinus koraiensis, 16(14%) was Pinus densiflora, 5(4.4%) was Abies holophylla, 2(1.8%) was Quercus sp., and 1(0.9%) was Pinus rigida. 2. The pillars from Sudarajang were consist of various species such as Pinus densiflora, Pinus Koraiensis, Abies holophylla, Quercus sp., and Zelkova serrata, whereas all 47 out of 48 pillars from Beopbojeon were consist of only one species-Zelkova serrata. 3. We can be inferred from the characteristics of the identified species that Beopbojeon whose pillars are made of only Zelkova serrata was built at least before the mid-Koryo dynasty followed by Sudarajang, but Dongsaganjang and Seosaganjang might be built far later than that time.