using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Security;

namespace Myproject.Security
{
    public class CustomRoleProvider : RoleProvider
    {

    }
}

public override string[] GetRolesForUser(string username)
        {
            using (DatabaseEntities db = new DatabaseEntities())
            {
                User user = db.Users.FirstOrDefault(u => u.UserName.Equals(username, StringComparison.CurrentCultureIgnoreCase));
 
                var roles = from ur in user.UserRoles
                            from r in db.Roles
                            where ur.RoleId == r.Id
                            select r.Name;
                if (roles != null)
                    return roles.ToArray();
                else
                    return new string[] {}; ;
            }
        }

public override bool IsUserInRole(string username, string roleName)
        {
            using (DatabaseEntities db = new DatabaseEntities())
            {
                User user = db.Users.FirstOrDefault(u => u.UserName.Equals(username, StringComparison.CurrentCultureIgnoreCase));
 
                var roles = from ur in user.UserRoles
                            from r in db.Roles
                            where ur.RoleId == r.Id
                            select r.Name;
                if (user != null)
                    return roles.Any(r => r.Equals(roleName, StringComparison.CurrentCultureIgnoreCase));
                else
                    return false;
            }
        }

public override bool IsUserInRole(string username, string roleName)
        {
  return this.GetRolesForUser(username).Contains(roleName);
        }

<system.web>
    ...
    <rolemanager cacherolesincookie="true" defaultprovider="CustomRoleProvider" enabled="true">
        <providers>
            <clear />
            <add name="CustomRoleProvider" type="Myproject.Security.CustomRoleProvider" />
        </providers>
    </rolemanager>
    ...
</system.web>

using System;
using System.Web.Mvc;
 
namespace MyProject.Areas.Admin.Controllers
{
    [Authorize(Roles = "Administrators")]
    public class HomeController : Controller
    {
        //
        // GET: /Admin/Home/
 
        public ActionResult Index()
        {
            return View();
        }
 
    }
}