<script language="JavaScript">
<!--
function make(){
    text = document.createElement("input");
    text.setAttribute("type","button");
    text.setAttribute("value","ボタン1");
    document.getElementById("nobr").appendChild(text);
    document.getElementById("makeBtn").disabled = true;
}
// -->
</script>
<input type="button" id="makeBtn" value="子ノード作成" onclick="make()" />