Document.TextEncoding (Word)

Returns or sets the code page, or character set, that Microsoft Word uses for a document saved as an encoded text file.

The TextEncoding property sets text encoding separately from HTML encoding, which you can set using the Encoding property. To set text encoding for all documents saved as text files, use the DefaultTextEncoding property.

Sub EncodeText() 
 ActiveDocument.TextEncoding = msoEncodingJapaneseShiftJIS 
End Sub