Sub PDF_Word()
Dim chemin$, doc$, pdf$, Wapp As Object
chemin = ThisWorkbook.Path & "\" 'à adapter
doc = "Mon document.docx" 'à adapter
pdf = Left(doc, InStrRev(doc, ".") - 1) & ".pdf"
Application.DisplayAlerts = False 'si le fichier Word est ouvert
On Error Resume Next
Set Wapp = GetObject(, "Word.Application")
If Wapp Is Nothing Then Set Wapp = CreateObject("Word.Application")
With Wapp.Documents.Open(chemin & doc)
.ExportAsFixedFormat chemin & pdf, ExportFormat:=17 '17 => wdExportFormatPDF
.Close False
If Wapp.Documents.Count = 0 Then Wapp.Quit
End With
End Sub