function IsAdmin: Boolean;
const 
  SECURITY_NT_AUTHORITY: TSIDIdentifierAuthority = 
  (Value: (0, 0, 0, 0, 0, 5)); 
  SECURITY_BUILTIN_DOMAIN_RID = $00000020; 
  DOMAIN_ALIAS_RID_ADMINS     = $00000220; 

var 
  hAccessToken: THandle; 
  ptgGroups: PTokenGroups; 
  dwInfoBufferSize: DWORD; 
  psidAdministrators: PSID; 
  x: Integer; 
  bSuccess: BOOL; 
begin 
  Result := False; 
  bSuccess:=False; 
  ptgGroups:=nil; 
  psidAdministrators:=nil; 
  try 
    bSuccess := OpenThreadToken(GetCurrentThread, TOKEN_QUERY, True, 
      hAccessToken); 
    if not bSuccess then 
    begin 
      if GetLastError = ERROR_NO_TOKEN then 
      bSuccess := OpenProcessToken(GetCurrentProcess, TOKEN_QUERY, 
        hAccessToken); 
    end; 
    if bSuccess then 
    begin 
      GetMem(ptgGroups, 1024); 
      bSuccess := GetTokenInformation(hAccessToken, TokenGroups, 
        ptgGroups, 1024, dwInfoBufferSize); 
      if bSuccess then 
      begin 
        AllocateAndInitializeSid(SECURITY_NT_AUTHORITY, 2, 
          SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS, 
          0, 0, 0, 0, 0, 0, psidAdministrators); 
        {$R-} 
        for x := 0 to ptgGroups.GroupCount - 1 do 
          if EqualSid(psidAdministrators, ptgGroups.Groups[x].Sid) then 
          begin 
            Result := True; 
            Break; 
          end; 
        {$R+} 
      end; 
    end; 
  finally 
    if bSuccess then 
      CloseHandle(hAccessToken); 
    if Assigned(ptgGroups) then 
      FreeMem(ptgGroups); 
    if Assigned(psidAdministrators) then 
      FreeSid(psidAdministrators); 
  end; 
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
if  IsAdmin then showmessage('true') else showmessage('false') 
end;