The first-order relativistic effects such as relativistic correction to the kinetic energy, spin-orbit interaction and one-and two-body Darwin terms for the ground and excited states of confined H−, He, Li+ and Be++ atoms have been investigated. The results reveal that impurity charge and dot radius have a strong influence on the relativistic effects. In the strong confinement region, when the dot radius is further decreased, the magnitude of relativistic effects increases rapidly. Similarly, as the impurity charge increases, the relativistic effects increase substantially. In the electronic configuration 1,3S (1s2s), spin-orbit interaction energy and total Darwin energy for the case of triplet are lower than the singlet case. In addition, when the dot radius is large enough, the results for the relativistic effects approach to the corresponding values of free atom.