The increased interest in hemispherical quantum dots [1-2] is caused by the outstanding properties and potential applications of such nanostructures in optoelectronic devices such as photodetectors, solar cells, and others. This study presents a simple model within the effective mass approximation to describe the effect of an external electric field on the energy structure and wave functions of electrons and holes in type II hemispherical quantum dots. The case of a uniform electric field perpendicular to the surface on which a hemispherical quantum dot is grown is considered. The solutions of the Schrödinger equation were obtained by the matrix method on the orthogonal basis of the exact wave functions of quasiparticles in this nanostructure without the influence of an electric field. It is shown that the shift of the energy levels of the electron localized in the core of the nanostructure depends linearly on the electric field. And the shift of energy levels of the hole is non-linear. The values of the wave functions expansion coefficients show that new states of quasiparticles are formed from several old neighboring states, the number of which increases with increasing electric field intensity. At the same time, the basic state, which makes the greatest contribution to the formation of a new state, can change. Such a change in the symmetry of the quasiparticle state occurs in the case of energy levels anticrossing. As a result, the oscillators strength of quantum transitions, which are forbidden in the absence of an electric field, increase significantly. The optical transition energies and the absorption coefficient dependences on external electric field are investigated. 1. Wu, S., Song, Y., Han, S., Yang, Y., Guo, F., & Li, S. Chinese Physics B, 2021, 30, 053201. 2. Mohammadi, S. A., Khordad, R., & Rezaei, G. Physica E: Low-Dimensional Systems and Nanostructures, 2016, 76, 203–208.