The present invention provides a kind of pyrazolopyrimidine (pyrazolopyrimidine) derivative or its salt etc. pharmaceutically allowed, and is used as prevention and/or the therapeutic agent of skin disease, and is indicated with following formula (I):In formula, R1 expression-NR1aR1b (in formula, R1a and R1b are identical or different, indicate hydrogen atom, aralkyl etc.) etc.,[in formula, k and m respectively indicate 0~2 integer to R2 expression (Ya), and n indicates that 0 to 4 integer, L indicate singly-bound etc., R5 indicates that halogen etc., R6 indicate that aryl etc., X indicate CR8 (in formula, R8 indicates hydrogen atom etc.) etc., R7 indicates hydrogen atom etc.] etc.R3 expression-SO2R13a [in formula, R13a indicates lower alkoxy ,-NR13dC (=O) R13e (in formula, R13d indicates that hydrogen atom etc., R13e indicate low alkyl group etc.) etc.] etc.,R4 indicates hydrogen atom etc. }.本發明提供一種吡唑并嘧啶(pyrazolopyrimidine)衍生物或其藥學上所容許之鹽等，其用作皮膚疾病之預防及/或治療劑，且以下述式(I)表示：{式中，R1表示-NR1aR1b(式中，R1a及R1b相同或不同，表示氫原子、芳烷基等)等，R2表示式(Ya)[式中，k及m分別表示0～2之整數，n表示0至4之整數，L表示單鍵等，R5表示鹵素等，R6表示芳基等，X表示CR8(式中，R8表示氫原子等)等，R7表示氫原子等]等，R3表示-SO2R13a[式中，R13a表示低級烷氧基，-NR13dC(=O)R13e(式中，R13d表示氫原子等，R13e表示低級烷基等)等]等，R4表示氫原子等}。
