Novel therapeutic agents for myeloma are provided. A therapeutic agent for multiple myeloma containing a pyrazole compound represented by the formula (1): wherein R 1 is C 1 -C 6 alkyl, C 1 -C 6 alkyl substituted with R 17 , C 1 -C 6 haloalkyl, phenyl, phenyl substituted with a R 11 's or the like, R 2 is a hydrogen atom, C 1 -C 6 alkyl, phenyl or phenyl optionally substituted with e R 21 's or the like, R 3 is a hydrogen atom or the like, X is a single bond or -(CR 6 R 7 ) n -, each of R 4 and R 5 is independently C 1 -C 6 alkyl or the like, R 6 and R 7 are hydrogen atoms or C 1 -C 6 alkyl, R 8 is phenyl, phenyl optionally substituted with k R 81 's or the like, a tautomer of the compound or a pharmaceutically acceptable salt or solvate thereof, as an active ingredient.
