To provide a structure with a connector pulling-out made difficult which is insertion-coupled and locked to a connector housing part of an electric connecting box.

A connector locking protrusion is fitted in protrusion at a connector housing part inner face of an electric connection box, as well as a locked piece having flexibility is fitted in protrusion on a housing outer face of a connector for insertion-coupling and connecting to the connector housing part. The locked protrusion fitted at the locked piece is locked to the connector locking protrusion, and on the other hand, a cover attaching part is fitted in protrusion at a peripheral edge along a side of the connector housing part of a connector locking protrusion side. After insertion-coupling and locking the connector to the connector housing part, a cover to be fastened and fixed at a cover attaching part by a screw is provided. The cover comprises an interference rib protruded outward of a connector insertion opening, and a locking holding part bending from a tip of the interference rib to be inserted into a gap between the outer face of the connector housing and the locked piece.