The present invention aims to provide a novel compound which has CGRP receptor antagonist activity and which is useful for the treatment of various diseases mediated by CGRP receptors. That is, the present invention relates to the pyrrolidine derivatives represented by the following formula (I) or a pharmaceutically acceptable salt thereof. In the formulae, W is ring, X is a carbon atom or the like, Y1 to Y4 are carbon atoms or the like, and R1 to R7 is alkyl or the like. The compounds of the present invention or a pharmaceutically acceptable salt thereof have an excellent CGRP receptor antagonist activity, and thus are useful as agents for the treatment of various diseases mediated by CGRP receptors.