The interband light absorption in spherical quantum dot (QD) of semiconductors connected with the charged and neutral exciton-donor complexes are studied theoretically. The oscillator strength for interband optical transition from valence band to the ground state of excitondonor complex in spherical QD has been investigate. The calculations were performed in the cases of infinite and finite potential barrier of QD. The dependences of the oscillator strength on the radius of the QD were obtained. It was shown that the quantum confinement gives rise a giant oscillator strength per impurity.