Poland, the reigning European champions, remain unbeaten in the tournament and have not dropped a set in four matches.
They will face Bulgaria on Wednesday in their final group-stage match.
Elsewhere on Tuesday, the leaders of the other groups also won. Italy defeated the Czech Republic 3-1 in Group A, Finland beat the Netherlands 3-2 in Group C, and France defeated Germany 3-0 in Group D.
The European Championship is being co-hosted by Finland, Romania, Bulgaria and Italy.
Poland will play its group-stage and round-of-16 matches in Sofia, while the quarterfinals and semifinals will also be held in Bulgaria.
The decisive matches will be played in Milan.
This year's tournament is also the first opportunity under new qualification rules to secure a place at the 2028 Olympic Games in Los Angeles. Only the European champion will earn an Olympic berth through the tournament.
(gs)
Source: IAR/PAP