The present invention provides a pyrazolopyrimidine derivative represented by formula (I) {wherein R 1 represents -NR 1a R 1b (wherein R 1a and R 1b are the same or different and each is a hydrogen atom, aralkyl, or the like), or the like, R 2 represents formula (Ya) [wherein k and m each represents an integer of 0 - 2, n represents an integer of 0 - 4, L represents a single bond or the like, R 5 represents halogen or the like, R 6 represents aryl or the like, X represents -CR 8 (wherein R 8 represents a hydrogen atom or the like), or the like, and R 7 represents a hydrogen or the like], or the like, R 3 represents -SO 2 R 13a [wherein R 13a represents lower alkoxy, - NR 13d C(=O)R 13e (wherein R 13d represents a hydrogen atom or the like, and R 13e represents lower alkyl or the like), or the like], or the like, and R 4 represents a hydrogen atom or the like}, or a pharmaceutically acceptable salt thereof, useful as a prevention and/or therapeutic agent for skin diseases, and the like.
