Lissencephaly therapeutic agent

A method for treating lissencephaly comprising administering to a lissencephaly patient or a pregnant woman who is carrying a lissencephaly fetus, a compound represented by the general formula (I):

• wherein R1 is a linear or branched C1-6 alkyl substituted with C1-6 alkoxy;
• a linear or branched C1-6 alkyl substituted with a heterocyclic group;
• a heterocyclic group, or a group represented by the formula (IIa):
• wherein R4 is a linear or branched C1-6 alkyl;
• R5 is C1-4 alkylene, and m is an integer of 1 to 6;
• R2 is a linear or branched C1-6 alkyl optionally substituted with phenyl;
• and
• R3 is a linear or branched C1-6 alkyl optionally substituted with halogen, a C1-6 alkoxy, or phenyl;
• a C3-6 cycloalkyl optionally substituted with halogen, C1-6 alkoxy, or phenyl;
• a condensed polycyclic hydrocarbon;
• or hydrogen.