Why do holes move in the opposite direction from electrons in an electric field?

In a semiconductor, a hole represents a missing electron within the crystal's covalent bond structure. When an electron moves to fill this vacancy, it leaves behind a new hole at its previous location, effectively causing the position of the deficiency to shift.1

Because a missing electron is equivalent to a positive electric charge, this shifting deficiency behaves like a positively charged particle. Under the influence of an electric field, negatively charged electrons are attracted toward the positive potential, while the positively charged holes are attracted toward the negative potential. Consequently, holes move in the direction opposite to that of electrons.21

While both act as charge carriers, holes generally move more slowly than electrons because they function within the tightly bound valence band rather than the conduction band.21