From Tokyo, you can take a domestic flight to Hiroshima Airport. From the airport, you can use the Hiroshima Airport Limousine Bus to Hiroshima Bus Center which takes about 50 minutes. From there, Hiroshima Peace Memorial Park is a 15-minute walk or a short bus/tram ride away.
Travel to Hiroshima using the JR Sanyo Shinkansen Line from major cities like Tokyo, Osaka, and Fukuoka. Once you arrive at Hiroshima Station, take the Hiroshima Electric Railway (tram). The most convenient lines are the 2 or 6 to Genbaku-Domu Mae (Atomic Bomb Dome) stop, which is right next to the park.
If you are coming from within Hiroshima prefecture or close regions, local JR trains and buses are available and will connect you to Hiroshima Station, from where you can follow the above instructions for the tram.
Hiroshima is served by highway buses from various cities. Once you arrive in Hiroshima, local buses can be taken to the area surrounding the Peace Memorial Park. Look for bus services going to the A-Bomb Dome or Peace Memorial Park.
Renting a car is also an option, though driving in the city may not be necessary. Parking near the Peace Memorial Park might be challenging due to the area being a busy tourist spot.
From Hiro Pria (Hiroshima Prefectural Industrial Promotion Hall), the Peace Memorial Park is approximately a 25-minute walk. It is a pleasant walk through the city, allowing you to see many sights along the way.