The invention relates to a toothbrushing monitoring device (18). In order to obtain an efficient monitoring device, the monitoring device comprises: an input device (21), an acceleration sensor, a signal conditioner, a memory, a comparator which compares the numbers of brushing cycles registered by each teeth surface specific counter during brushing with corresponding reference values maintained in said memory, and an output device (27) which indicates that the brushing of the teeth region (L-U) in question is accepted.