The index had risen in April by 0.5 percent on a 12-month basis, the federal statistics office Destatis said in a statement.
Using the Harmonised Index of Consumer Prices (HICP) -- the yardstick used by the European Central Bank -- inflation in Germany also rose by 0.7 percent year-on-year in May, still way under the ECB's annual inflation target of just below two percent.
The May data are still only preliminary, since they are based on consumer price statistics from only six of Germany's 16 regional states.
Final data from all 16 states will be published on June 16, Destatis said.
The data nevertheless appear to confirm that the ECB's monetary policy measures are slowly beginning to push up inflation.
In March, the ECB embarked on a massive trillion euro ($1.1 trillion) bond purchase programme to ward off deflation and end stagnation in the eurozone economy.