A compound (chemotherapeutic agent) that is effective in the prevention and treatment of hyperlipidemia, obesity, or similar diseases. Claim 1: a phenyl diazo compound represented by formula (1),or a pharmaceutically acceptable salt thereof, where R¹ is (1-1) hydrogen, (1-2) pyrazolyl, (1-3) pyrimidinyl, (1-4) pyridyl having one or two substituents selected in each case in form independent from the group consisting of halogen, cyano, C₁₋₆ alkyl, C₁₋₆ alkylsulfonyl, and C₁₋₆ alkyl substituted by halogen, (1-5) oxazolyl having one or more C₁₋₆ alkyl groups, (1- 6) pyrazinyl optionally substituted with at least one group selected from the group consisting of halogen and C₁₋₆ alkyl,(1-7) phenyl having one or two substituents independently selected in each case from the group consisting of halogen and C₁₋₆ halogen substituted alkyl, (1-8) (1-pyridine oxide) yl having one or two substituents independently selected in each case from the group consisting of halogen and C₁₋₆ halogen substituted alkyl, (1-9) halogen substituted thiazolyl, (1-10) C₁₋₆ alkyl substituted isoxazolyl, (1-11) 1,2,4-oxadiazolyl substituted with C₃₋₈ cycloalkyl, or (1-12) phenyl； R² represents hydrogen or C₁₋₆ alkoxy； R³ is (3-1) hydrogen, (3-2) C₁₋₆ alkoxy,(3-3) C₁₋₆ alkoxy-C₁₋₆ alkoxy, (3-4) C₁₋₆ alkyl, (3-5) halogen, (3-6) benzyloxy, or (3-7) hydroxy； R⁴ is (4-1) pyridyl which optionally has at least one substituent selected from the group consisting of halogen, cyano, hydroxy, pyrrolidinyl, C₁₋₆ alkyl, C₁₋₆ alkylthio, C₁₋₆ alkylsulfonyl, C₁₋₆ alkoxy, and C₁₋₆ alkyl substituted by halogen, (4-2) C₃₋₁₀ cycloalkyl optionally having one or two substituents independently selected in each case from the group consisting of halogen and C₁₋₆ alkyl, or (4-3 ) lower alkyl； R⁵ is (5-1) hydrogen, (5-2) C₁₋₆ alkyl,or (5-3) C₁₋₆ alkoxy； R⁶ is (6-1) hydrogen, (6-2) C₁₋₆ alkoxy-C₁₋₆ alkyl, or (6-3) C₁₋₆ alkyl optionally substituted with one or more C₃₋₁₀ cycloalkyl groups, where R⁶ binds to only one of N in posit
