Dim PrtSet, Prt, Locator, Service, MesStr, Fs, Txt
File        = "defaut_printer.txt"
Set Locator = CreateObject("WbemScripting.SWbemLocator")
Set Service = Locator.ConnectServer
Set PrtSet  = Service.ExecQuery("Select * From Win32_Printer")
Set Fs      = WScript.CreateObject("Scripting.FileSystemObject")
If Fs.FileExists(File) Then Fs.DeleteFile File, True
Set Txt     = Fs.OpenTextFile(File, 2, True)

For Each Prt In PrtSet
    '通常使うプリンターを取得
    If Prt.Default Then
        Txt.WriteLine Prt.Caption
        MsgBox "通常使うプリンタ: " & Prt.Caption
    End If
Next

Txt.Close
Set Txt     = Nothing
Set Fs      = Nothing
Set Prt     = Nothing
Set PrtSet  = Nothing
Set Service = Nothing
Set Locator = Nothing