The present invention relates to a compound of formula I: wherein: R 1 is a hydrogen atom, F, CN, etc.; R 1 ' is a hydrogen atom or lower alkyl which may be substituted; R 2 is O, S, SO, SO 2 , etc.; R 3 is a phenyl which may be substituted; X 1 , X 2 , and X 3 each independently CH, N, etc. provided, however, that among X 1 , X 2 and X 3 , the number of nitrogen is 0 or 1; W is the following residue: wherein: W 1 , W 2 , and W 3 each independently CH, N, etc., or a pharmaceutically acceptable salt or ester thereof.