Eighty percent of employees say managers are unnecessary, a national survey on manager-employee relationships found.

The survey of more than 2,000 employees by Ultimate Software found that 75 percent of employees say approachability is the most important quality in an effective manager, but only half of 10 employees say they have an approachable manager.

For 93 percent of employees, trust in their direct boss is essential to staying satisfied at work, and over half of employees surveyed say that if they aren’t satisfied at work, they can’t put forth their best effort.

Ultimate Software, based in Weston, Fla., said the employee-manager relationship “matters a great deal when it comes to job satisfaction and retention.”

The survey, released Monday, is “a wake-up call for companies of all sizes to get serious about better training, coaching, and guidance for managers, so these relationships remain strong,” said Adam Rogers, chief technology officer at Ultimate Software, which specializes in human resources software.

Jason Dorsey, president and co-founder of the Center for Generational Kinetics, a research organization in Austin, Texas, said the results “highlight the long-standing belief that people don’t leave companies, they leave managers.” He said the issue is a “serious concern that affects everyone in the workforce and it’s something all companies should focus on fixing before they end up losing great leaders and valuable talent.”

Ultimate’s survey pointed to a significant gap in managers’ and employees’ perceptions: 80 percent of managers surveyed think they’re transparent with their direct reports, yet only 55 percent of employees agree. And while most employees say they feel comfortable communicating, 57 percent of managers wish their employees would be more open with what’s on their mind.

One problem, according to the survey, is that less than half of managers report having a mentor who gives them guidance on how to be a better leader, and 45 percent have never received management training.