A connector engaging structure which prevents male and female connectors from being insufficiently engaged with each other, and which positively prevents the connector housing from being damaged. The connector engaging structure 1 is designed as follows. In engaging a second connector 3 with a first connector 2, a cantilevered arm 44 formed in an outer housing, which is a part of the second connector, is locked to a locking protrusion 16 of the first connector. Next, a locking arm 25 forming an inner housing 21, which is a part of the second connector 3, is engaged with an engaging groove 15 formed in the first connector 2. With the outer housing 22 moved by the elastic force of a spring member 35, the lock arm 25 is held down so that the first and second connectors are completely engaged with each other.