출처 : Torry's Delphi

// This code works also with a TListBox

var
  Bitmap1, Bitmap2, Bitmap3, Bitmap4: TBitmap;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ComboBox1.Style := csOwnerDrawVariable;

  //Set height of one item
  ComboBox1.ItemHeight := 20;

  //load all bitmaps

  Bitmap1 := TBitmap.Create;
  Bitmap1.LoadFromFile('chem16.bmp');

  Bitmap2 := TBitmap.Create;
  Bitmap2.LoadFromFile('chip16.bmp');

  Bitmap3 := TBitmap.Create;
  Bitmap3.LoadFromFile('factry16.bmp');

  Bitmap4 := TBitmap.Create;
  Bitmap4.LoadFromFile('skylin16.bmp');

  //assign bitmaps with item objects - caption of the items: Bitmap 1 - Bitmap 4

  ComboBox1.Items.AddObject('Bitmap 1', Bitmap1);
  ComboBox1.Items.AddObject('Bitmap 2', Bitmap2);
  ComboBox1.Items.AddObject('Bitmap 3', Bitmap3);
  ComboBox1.Items.AddObject('Bitmap 4', Bitmap4);
end;

procedure TForm1.ComboBox1DrawItem(Control: TWinControl; Index: Integer;
  Rect: TRect; State: TOwnerDrawState);
var
  Bitmap: TBitmap;
  Offset: Integer;
begin
  offset := 0;
  with ComboBox1.Canvas do
  begin
    FillRect(Rect);
    Bitmap := TBitmap(ComboBox1.Items.Objects[Index]);
    if Bitmap <> nil then
    begin
      //copy bitmap to combobox coordinate
      BrushCopy(Bounds(Rect.Left + 2, Rect.Top + 2, Bitmap.Width,
        Bitmap.Height), Bitmap, Bounds(0, 0, Bitmap.Width,
        Bitmap.Height), clred);
      Offset := Bitmap.Width + 8;
    end;
    //Set a caption to each item
    TextOut(Rect.Left + Offset, Rect.Top, Combobox1.Items[Index]);
  end;
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  //free all bitmap objects
  bitmap1.Free;
  bitmap2.Free;
  bitmap3.Free;
  bitmap4.Free;
end;

정말 감사합니다. 토리스 델파이에 있었군요~~
^^ 너무너무 감사합니다.