A quantum dot includes a seed and a core enclosing the seed. The core is grown from the seed to improve size uniformity of the core. The seed includes a first compound without Cd. The first compound may be GaP. The core may include a second compound including elements from group XIII and group XV. The second compound may be InP. The quantum dot may also include a first shell of a third compound enclosing the core. The third compound may be ZnSe or ZnS. The quantum dot may also include a second shell of a fourth compound enclosing the first shell. The fourth compound may be ZnS when the third compound is ZnSe. Embodiments also relate to a quantum dot including first to third elements selected from XIII group elements and XV group elements and fourth to sixth elements selected from XII group elements and XVI group elements.