A majority of New York voters says the city is becoming “less safe” under Mayor de Blasio — while they believe his predecessors, Rudy Giuliani and Mike Bloomberg, made the Apple a better place to live, a poll to be released Monday reveals.

Of those who had an opinion, 55 percent said they thought the city was less safe under the current mayor, while only 28 percent thought it was safer now, according to the survey last week of 517 registered voters by 1NY Together, a new not-for-profit civic group started by real-estate honcho Paul Massey.

Fifty-eight percent said the city was safer under Mayors Giuliani and Bloomberg, while 24 percent said it was less safe. The rest of the respondents said they were undecided. The results were consistent across all five boroughs.

Of the three mayors, voters gave Giuliani the highest marks on quality-of-life improvement (39 percent), with Bloomberg rated second (31 percent) and de Blasio third (21 percent).

A majority of voters also opposes the City Council bill to wipe out 700,000 summonses given to people who have committed minor crimes, such as urinating in public, disorderly conduct, carrying
marijuana or loitering near schools.

A 54 percent majority said the offenders should be prosecuted; 29 percent think they should be “let off the hook.”