The present invention provides a 1,4-disubstituted imidazole derivative of formula (1'): wherein ring Q1 is optionally-substituted C6-10 aryl group, etc.； R1 and R2 are independently hydrogen atom, etc.； W1 is optionally-substituted C1-4 alkylene group； W2 is -NR3aC(O)- wherein R3a is hydrogen atom or C1-6 alkyl group, etc.； ring Q2 is 5- to 10-membered heteroaryl group, etc.； W3 is optionally-substituted C1-4 alkylene group, etc.； n is 1, 2, 3, 4, or 5； R4 is independently halogen atom, optionally-substituted C1-6 alkyl group, etc.； R5 is hydroxy group, etc.； and a pharmacologically acceptable salt thereof, which have a potent action inhibiting the sphere-forming capacity of cancer cells and are useful as an orally-available antitumor agent.本發明提供一種表現出優異之癌細胞球結構形成能力抑制作用、作為可經口投予之抗腫瘤劑而有用之式(1')所表示之1,4-二取代咪唑衍生物及其製藥學上容許之鹽。[式中，環Q1表示可經取代之C6-10芳基等；R1及R2獨立地表示氫原子等；W1表示可經取代之C1-4伸烷基；W2表示-NR3aC(O)-等(此處，R3a表示氫原子或C1-6烷基)；環Q2表示5員~10員之雜芳基；W3表示可經取代之C1-4伸烷基等；n表示1、2、3、4或5；R4於存在複數個之情形時分別獨立地表示氫原子、可經取代之C1-6烷基等；R5表示羥基等]
