You’re probably sick of hearing it: “Employees don’t leave companies, they leave bad bosses.” But it’s true. And the reason people leave bad managers? A lack of trust.  
Here’s what Carolyn O’Hara, writing on the Harvard Business Review blog, identifies as four ways managers can prove their trustworthiness in their charges’ eyes.

Trustworthy Trait 1: Be transparent

Of course, there are certain things a manager can’t disclose, like salary data. And staffers have to understand that. But on most other things, managers want to be as transparent as possible.
That means being honest about company goals, performance metrics and overall performance.
Not only does that increase trust between the supervisor and staffers, but there’s an added bonus: It keeps the rumor mill under control. When staffers know they can count on a straight answer from their immediate boss, there’s a lot less room for speculation and those productivity-damaging rumors.
Tip: Managers might also try to offer some of this information up before staffers ask. It shows employees their boss’s level of trust.

Trustworthy Trait 2: Encourage, rather than command

Yes, the manager’s the one in charge. But the most trustworthy bosses are secure enough in that that they know that doesn’t mean bossing people around.
The best leaders function more like coaches. So rather than telling staffers the way exactly how a specific task must be done, sometimes it pays to give them the freedom come up with the most efficient approach.
Managers just need to be sure they make expectations clear so folks have a framework to work within.

Trustworthy Trait 3: Admit mistakes

This can be the toughest one, no matter who you are. No one wants to admit they were wrong or handled something improperly.
But managers can build up a lot of credibility with their team if they own up to a mistake.
You know how many people who say they often think more favorably of a company that made a mistake and corrected it than the company that never made a mistake at all? That’s what happens when a manager admits a mistake.
It serves as a bonding opportunity, yes. So when a boss makes a mistake, it’s crucial he/she owns  up to it right away.
But it can be used as a teaching opportunity, too. When a staffer makes a misstep, the manager  might consider sharing a time when he faltered. It shows empathy and helps build stronger team bonds.

Trustworthy Trait 4: Never badmouth anyone

This is an urge managers need to resist at all cost. Even when they’re attempting to commiserate with a staffer, they should never badmouth someone else.
The underlying message is: If you’ll say something behind James’ back, you’ll probably won’t hesitate to say something negative about me the minute my back is turned.