Tetranychoid mites found from Korea until now are 42 species belonging to 12 genera, 2 families as follows: 1 Bryobia japonica Ehara et Yamada, 2. B. praetiosa Koch, 3. B. rubrioculus(Scheuten), 4. Petrobia latens(Muller), 5. Aponychus corpuzae Rimando, 6. A firmianae(Ma et Yuan). 7. Panonychus citri(McGregor), 8. P. ulmi(Koch), 9. Eotetranychus carpini Oudemans, 10. E. hicoriae(McGregor), 11. E. populi(Koch), 12. E. rubiphilus (Reck), 13. E. sexmaculatus (Riley), 14. E. smithi Pritchard et Baker, 15. E. tiliarium (Hermann), 16. E. uchidai Ehara, 17. Schizotetranychus bambusae Reck, 18. S. celarius(Banks), 19. S. leguminosus Ehara, 20. Oligonychus aceris(Shimer), 21. O. clavatus(Ehara), 22. O. hondoensis(Ehara), 23. O. ilicis(McGregor), 24. O. karamatus(Ehara), 25. O. orthius Rimando, 26. O. peridtus Pritchard et Baker, 27. O. shinkajii Ehara, 28. O. pustulosus (Ehara), 29. O. ununguis(Jacobi), 30. O. sp. 31. Tetranychus kanzawai Kishida, 32. T. phaselus Ehara, 33. T. truncatus Ehara, 34. T. urticae Koch, 35. T. vienensis Zacher, 36. Aegyptobia nothus Pritchard et Baker, 37. Pentamerismus taxi (Haller), 38. P. oregonensis McGregor, 39. Brevipalpus californicus(Banks), 40. B. lewisi McGregor, 41. B. obovatus Donnadieu, 42. Tenuipalpus zhizhilashviliae Reck. On the above species, a taxanomic key was made and ecological data including distribution and host plant are presented in this paper.