The group said its help-wanted index, which measures advertising volume in 51 major newspapers across the country, dropped 3 points to 35 from 38 in March. The board noted the index stood at 47 one year ago.
Economists on Wall Street were expecting the index to remain unchanged during the month.
In addition to providing insight on the general strength of the economy, the report gives a sense of how many jobs employers are trying to fill.
If that number is relatively high, it could mean there is a shortage of available workers and companies may have to offer higher wages to attract them.
The board said over the last three months, help-wanted advertising declined in all nine regions of the country.
The steepest declines occurred in the East South Central, where help-wanted ads plunged 32 percent, the Middle Atlantic region, where ads sank 18.4 percent, the Pacific region, where ads fell 16.4 percent and in the New England region of the country, where help-wanted advertising fell 15.7 percent.
Conference Board Economist Ken Goldstein said: "April may represent a low point for the ailing labor market. After initial unemployment claims revealed a big rise in layoffs, want-ad volume significantly declined from already very depressed levels.
"Clearly, businesses have been busy laying off workers and scaling back already greatly reduced plans to hire. If the overall economy remains weak heading into the third quarter, a return to job growth earlier than the fourth quarter doesn't seem likely."