since a front antenna 33 performs road - to - vehicle communication and vehicle - to - vehicle communication with oncoming vehicles , a nondirectional antenna enables effective communication in communication distances . vehicle - to - vehicle communication with rearward vehicles by a rear antenna 37 needs long communication distances compared with road - to - vehicle communication and vehicle - to - vehicle communication with oncoming vehicles . the rear antenna 37 can also perform communication effectively with rear vehicles since what is selected is a directional one that can provide longer communication distances than a nondirectional one and that has directionality rearward of the vehicle . the front antenna 33 is disposed forward of a seat 7 , and the rear antenna 37 is disposed rearward of the seat 7 , which can inhibit an attenuation of electromagnetic waves due to the rider and the like . consequently , while being capable of performing road - to - vehicle communication effectively , vehicle - to - vehicle communication with rearward vehicles can also be performed effectively .