We developed a loop-mediated isothermal amplification (LAMP) assay for detecting Colletotrichum gloeosporioides, which causes anthracnose, in strawberry plants. Primer sets targeted the region from the gene encoding 5.8S ribosomal RNA to internal transcribed spacer 2, which is highly conserved in 25 Colletotrichum species in GenBank. Our results indicated that the LAMP assay, which uses template DNA prepared using microwave irradiation, is a simple and sensitive tool for detecting C. gloeosporioides in infected strawberry plants. Further, our results showed that the LAMP assay could differentiate Colletotrichum species such as C. acutatum, C. aenigma, and C. siamense.