Hi Tetsuya,

This is a bit tricky question. We all know that cell with Data Validation's
List includes items contained in a specified named range. Fine.

I, instead, want to do it with Custom using some kinf of formula, so that
users do NOT need to change the named range when a new item was added. Is
this possible?

This can be achieved by using a dynamic name to refer to the list. So instead
of the name being, say, =$A$1:$A$10, you define it as
=OFFSET($A$1,0,0,COUNTA($A:$A),1) (assuming there's nothing else in column
A).

That name will then automatically refer to however many items are in the list
that starts at A1, and the name can be used to drive DV's list.

Regards

Stephen Bullen
Microsoft MVP - Excel
www.oaltd.co.uk