The present invention provides a pyrazolopyrimidine derivative represented by formula (I){wherein R1 represents -NR1aR1b (wherein R1a and R1b are the same or different and each is a hydrogen atom, aralkyl, or the like), or the like,R2 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, R5 represents halogen or the like, R6 represents aryl or the like, X represents -CR8 (wherein R8 represents a hydrogen atom or the like), or the like, and R7 represents a hydrogen or the like], or the like,R3 represents -SO2R13a [wherein R13a represents lower alkoxy, - NR13dC(=O)R13e (wherein R13d represents a hydrogen atom or the like, and R13e represents lower alkyl or the like), or the like], or the like, andR4 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.
