Abstract: An electrical connector device comprising male and female housings and terminal seating detecting means. Each of the housings includes retaining means protruding in the form of a cantilever from each of partition walls, which define terminal chambers arranged in the form of a matrix composed of a plurality of rows and columns, and resiliently bendable in a flexure space. As male terminals, contained individually in the terminal chambers, and female terminals, adapted to be connected to the male terminals, engage the retaining means, the terminals are prevented from slipping out of the chambers. The terminal seating detecting means is fitted into the flexure space of the retaining means when the terminals are contained in their corresponding terminal chambers so that they normally engage the retaining means.