The present invention provides a compound of formula (I), wherein R 1 , R 2 , R 3 , R 4a , R 4b , R 5a and R 5b are as defined in the description, which has an autotaxin inhibitory activity, a pharmaceutical composition comprising the compound as an active ingredient, and a method of prevention or treatment of a disease involving autotaxin, which is characterized by administering the compound.