In April the index fell to 31.9 from 42.4 in March, according to Markit, a UK-based provider of financial information services.
Markit said that uncertainty was a key factor in May, with most companies not able to predict what production levels would be in a year's time.
A neutral PMI reading of 50 means that businesspeople in a country feel the economy will not change over the coming month.
A higher figure means the economy is expected to improve, while a PMI reading below 50 indicates that many think it will deteriorate.
Polish lawmakers at the end of April backed a plan to expand a massive relief and stimulus package of measures aiming to shield the economy from the coronavirus pandemic.
(pk)
Source: IAR