An electrical connector includes a base including a base housing, and a socket including a socket housing. Each of two socket side walls of the socket housing is provided with a first protrusion, and a distance L4 between two base side walls is equal to or larger than a distance L2 between the respective leading ends of the first protrusions. Each of two base side walls is provided with a first engagement projection on its inner surface, and a distance L1 between the respective leading ends of the first engagement projections is smaller than the distance L2 between the respective leading ends of the first protrusions, and the distance L1 is equal to or larger than a distance L3 between the two socket side walls. While the socket is completely accommodated in a socket accommodation chamber, each first protrusion is positioned below the corresponding first engagement projection.