Sub Sample()

    Dim wb As Excel.Workbook
    Dim ws As Excel.Worksheet
    Dim endCell As Excel.Range
    Set wb = ThisWorkbook
    Set ws = wb.Worksheets("Sheet1")
    
    '終端セルを取得したい列の最終セルを取得
    Set endCell = ws.Range("A65536")
    
    '最終セルでEndプロパティに定数xlUpを指定
    Set endCell = endCell.End(xlUp)

    'Rowプロパティで行数を表示
    MsgBox "終端セルは" & endCell.Row & "行目"

End Sub