I can not start nodemon

I'm trying to initialize with nodemon a project with access to postgre but it does not start when running the command. follows the error:

Error: listen EADDRINUSE :::3000
    at Object.exports._errnoException (util.js:1018:11)
    at exports._exceptionWithHostPort (util.js:1041:20)
    at Server._listen2 (net.js:1258:14)
    at listen (net.js:1294:10)
    at Server.listen (net.js:1390:5)                                                                         17:24)
    at EventEmitter.listen (C:\Users\ERNETWORK\Desktop\Ultimaversao\node_modules\express\lib\application.js:6
17:24)
    at Object.<anonymous> (C:\Users\ERNETWORK\Desktop\Ultimaversao\js\model.js:347:5)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)