Private Sub Worksheet_Change(ByVal Target As Range)
Dim Cel As Range, Plage As Range
Set Plage = Intersect(Target, Columns(2))
If Plage Is Nothing Then Exit Sub
For Each Cel In Plage
If Cel <> "" And Cel.Offset(0, -1) = "" Then Cel.Offset(0, -1) = Date
If Cel = "" Then Cel.Offset(0, -1).ClearContents
Next Cel
End Sub