Hiroshima-city is available two airport options,
#1 Hiroshima Airport
#2 Iwakuni Kintai Airport

#1. Hiroshima Airport Flight information: website
Haneda (HND) to Hiroshima Airport (HIJ)   about 1hour 30min flight  18 flight / day
Narita (NRT) to Hiroshima Airport (HIJ)      about 1hour 40min flight    4 flight / day
Hokkaido (CTS)  to Airport (HIJ)                 about 2hour 15min flight    2 flight / day
Sendai (SDJ) to Hiroshima Airport (HIJ)     about 1hour 40min flight    4 flight / day
Naha(OKA) to Hiroshima Airport (HIJ)        about 1hour 45min flight    1 flight / day
You can take Limousine bus to Hiroshima station, (50 min, JPY 1,370 oneway)

#2. Iwakuni Kintai Airport (IWK): website
Haneda(HND) to Iwakuni Kintai Airport      about 1hour 45min flight    5 flight / day
Naha(OKA) to Iwakuni Kintai Airport          about 1hour 45min flight    1 flight / day
You need take bus and JR train to go to Hiroshima station.
Airport Limousine bus (12 min, JPY 200) , JR local train (55min,JPY 770)
You can drop at Miyajima-guchi station (25min from JR train) on a way.