PURPOSE: To obtain a new tetra-substituted imidazolidinone derivative or its pharmaceutically acceptable salt or solvate useful as antitumor agents especially for the treatment of solid tumor.

CONSTITUTION: This compound of formula I {R1 is formula II, formula III [A is O, SOn, CH2SOn (n is 0 to 2), NR (R is methyl or ethyl) or the like; B is CH2, O, SOn or the like; D is CH, SOn or NR or the like, formula IV (Ra, Rb and Rc are each H, a halo, alkyl, alkoxy or CF3), formula V or formula VI (E is N, S or O)]; R4 and R5 are each H or an alkyl; R3 is H, a halo, alkyl or CF3; R2 is a halo, alkyl or CF3} or its pharmaceutically-acceptable salts or solvate e.g. 1-(indan-5-yl-sulfonyl)-3-(4-chlorophenyl)-4,5-dihydroxy-4-methyl- imidazolidin-2-one is obtained by reacting e.g. the compound of formula VII with a pyruvaldehyde.