The index, which fell 0.2 percent February and March, rose 0.1 percent in April, the research firm said.
The index is a comparison to the average monthly index in 2004, which was assigned an index value of 100.
The 0.1 percent gain for April was not enough to declare a turnaround for the eurozone, Conference Board economist Bert Colijn said. "After two months of declines," he said in a statement, the "economic environment remains sluggish."
"Confidence among businesses and consumers continues to be weak with unemployment continuing to increase while investments are not picking up," he said.
In the eurozone the "bright spot," is the service sector, Colijn said.
In the service sector, expectations have risen in five of the past six months, the Conference Board said.