The 1934 Mannin Moar (formally known as II Mannin Moar) was a Grand Prix that was held on 2 June 1934 at a street circuit in Douglas, Isle of Man, United Kingdom. It was the twelfth round of the 1934 Grand Prix season, but it did not count towards the championship. The race, contested over 50 laps of 3.659 mi, or 5.889 km, was won by Brian Lewis driving an Alfa Romeo Tipo B after starting from pole position.