Prices producers received were down 0.3 percent in both the 17-member, one-currency eurozone and the 27-member European Union, Eurostat said.
The decline follows a 0.6 percent month-to-month drop in the eurozone and a 0.7 percent decline in the EU in April.
From a year earlier, producer prices in May were stable in the EU and down 0.1 percent in the eurozone.
The agency said producer prices excluding the energy sector fell by 0.1 percent in both regions.
Prices excluding energy rose 0.5 percent in the eurozone and 0.6 percent in the EU from a year ago.
But energy prices fell 0.8 percent in the eurozone and 0.9 percent in the EU month to month. From a year earlier, energy prices isolated from other data, fell 1.8 percent in the eurozone and 2.2 percent in the EU as a whole.
Prices received for intermediate durable goods fell 0.5 percent in both regions on an annual basis, while prices for capital goods rose by 0.6 percent over the same period.