A toothbrush assembly with a sound generating function for providing excitement and entertainment to a user and for encouraging a young child to brush his or her teeth is provided. The toothbrush assembly has a contact-type switch and a sound generator. The contact-type switch has a swingable contact and generates a pulse when a power switch of the assembly is instantaneously closed for every swing of the swingable contact according to the tooth-brushing movement of a user. The sound generator has a counter for counting pulses from the contact-type switch and a sound recording and play back unit for generating a voice message or musical tone when the sum of the pulses counted by the counter reaches a predetermined value. The sound recording and play back unit of the sound generator outputs different voice messages or musical tones according to different predetermined values reached by the sum of the pulses counted by the counter.