Members of the order Psocoptera are known as psocids (commonly called booklice or bark lice). There are more than 5,500 species in 41 familes in three suborders. The suborder Psocomorpha is the largest suborder in Psocoptera, containing 25 of the 41 psocopteran families. Psocomorphan familes are classified into four groups: Epipsocetae, Caeciliusetae, Homilopsocidea and Psocetae. Families Caeciliusidae and Stenopsocidae belong to the group Caeciliusetae. The family Caeciliusidae is the largest family of Psocomorpha, and is widely distributed in all zoogeographical regions. Monophyly was not supported by any autapomorphy (Yoshizawa, 2002). The Stenopsocidae is distributed in the Afrotropical, Palearctic, Oriental, and Australian regions. Monophyly is well supported by the presence of the R1-R2+3 crossvein, M-CuA1 crossvein, and lateral pouch of the spermathecal sac (Yoshizawa, 2002). These families, Caeciliusidae and Stenopsocidae consist of about 676 described species in 32 genera and about 188 described species in 4 genera, respectively. In Asia, there were reported 337 species belonging to 11 genera and 154 species belonging to 4 genera from China (Li, 2000) and 22 species belonging to 6 genera and 7 species belonging to 2 genera from Japan (Yoshizawa, 2004), respectively, but there have not been known from Korea until now. This study is the first work to make the checklist of the Korean Psocoptera. Through this study, I have reported 2 species of families Caeciliusidae and Stenopsocidae new to Korea, respectively. Family Caeciliusidae Valenzuela oyamai (Enderlein, 1906) Paracaecilius japonicus (Enderlein, 1906) Family Stenopsocidae Cubipilis aphidiformis (Enderlein, 1906) Stenopsocus immaculatus (Stephens, 1836)