The present invention relates to a compound represented by Formula [I]: or a pharmaceutically acceptable salt or ester thereof, wherein R 1 and R 2 , which may be the same or different, are each a hydrogen atom, a lower alkyl group, a cycloalkyl group, or the like； R 3 and R 4 , which may be the same or different, are each a hydrogen atom, a lower alkyl group, NR a R b , a phenyl group, a lower alkyl group substituted with a phenyl group, a 4- to 7-membered aliphatic heterocyclic group, a lower alkyl group substituted with a 4- to 7-membered aliphatic heterocyclic group, a 5- or 6-membered aromatic heterocyclic group, a lower alkyl group substituted with a 5- or 6-membered aromatic heterocyclic group, or the like； and R 5 is a hydrogen atom, a cyano group, a halogen atom, or a lower alkyl group.
