A burn-in socket includes a base, a number of contacts received in the base, and a protecting device. The base has a first projection and a second projection. The protecting device is assembled to the base and moves from a first position to a second position relative to the base. The protecting device includes a planar bottom plate and a pair of spring arms extending upwardly from opposite sides of the bottom plate. Each spring arm has a first stopper for engaging with the first projection at the first position, and a second stopper for engaging with the second projection at the second position.