>>839
Private Sub CommandButton1_Click()
Dim y As Integer ←ここにDimを入れてない?
y = y + 1
Range("A1") = Format(y, "000")
End Sub


Dim y As Integer ←一番上の行に入れてみ。
Private Sub CommandButton1_Click()
y = y + 1
Range("A1") = Format(y, "000")
End Sub