Five mites of the genus Sennertia Oudemans, 1905: Sennertia alfkeni (Oudemans, 1900), Sennertia eximius sp. nov., Sennertia horrida (Vitzthum, 1912), Sennertia lauta Klimov and OConnor, 2007, Sennertia taiwanensis sp. nov., which are phoretic on carpenter bees (Genus Xylocopa) from Taiwan and Kinmen area, are described and illustrated. The species delimitation among the five Sennertia species using phylogenetic tree and genetic K2P distance analyses is well-defined. The species groups to which these bee mites belong, and their hosts in this area, are as follows: S. alfkeni (japonica-group): Xylocopa (Alloxylocopa) nr. appediculata, X. (Alloxylocopa) phalothorax and X. (Koptortosoma) ruficeps; S. eximius sp. nov. (cerambycina-group): X. (Biluna) auripennis, X. (Zonohirsuta) dejeanii and X. (Biluna) tranquebarorum; S. horrida (horrida-group): X. (Biluna) auripennis and X. (Biluna) tranquebarorum; S. lauta (horrida-group): X. (Zonohirsuta) dejeanii and X. (Biluna) tranquebarorum; S. taiwanensis sp. nov. (horrida-group): X. (Bombioxylocopa) bomboides.