Edit in JSFiddle

/**
 * tabletojson
 * jQuery plugin that reads an HTML table and returns a javascript object representing the values and columns of the table
 *
 * @author Daniel White
 * @copyright Daniel White 2013
 * @license MIT <https://github.com/lightswitch05/table-to-json/blob/master/MIT-LICENSE>
 * @link https://github.com/lightswitch05/table-to-json
 * @module tabletojson
 * @version 0.6.0
 */ (function(e) {
    e.fn.tableToJSON = function(t) {
        var n = {
            ignoreColumns: [],
            onlyColumns: null,
            ignoreHiddenRows: !0,
            headings: null
        };
        t = e.extend(n, t);
        var r = function(e) {
            return e !== undefined && e !== null ? !0 : !1
        }, i = function(n) {
            return r(t.onlyColumns) ? e.inArray(n, t.onlyColumns) === -1 : e.inArray(n, t.ignoreColumns) !== -1
        }, s = function(t, n) {
            var r = {};
            return e.each(n, function(e, n) {
                e < t.length && (r[t[e]] = n)
            }), r
        }, o = function(t) {
            var n = [];
            return e(t).children("td,th").each(function(t, s) {
                if (!i(t)) {
                    var o = e(s).data("override"),
                        u = e.trim(e(s).text());
                    n[n.length] = r(o) ? o : u
                }
            }), n
        }, u = function(e) {
            var n = e.find("tr:first").first();
            return r(t.headings) ? t.headings : o(n)
        }, a = function(n, i) {
            var u = [];
            return n.children("tbody,*").children("tr").each(function(n, a) {
                if (n !== 0 || r(t.headings)) if (e(a).is(":visible") || !t.ignoreHiddenRows) u[u.length] = s(i, o(a))
            }), u
        }, f = u(this);
        return a(this, f)
    }
})(jQuery); 



$('#convert').click(function() {
    var table = $('table').tableToJSON();
    console.log(table);
    alert(JSON.stringify(table));
}); 

table{
    width: 530px;
    border: 1px #E3E3E3 solid;
    border-collapse: collapse;
    border-spacing: 0;
}

table th {
    padding: 10px 5px;
    border:1px #E3E3E3 solid;
    background: #F5F5F5;
    font-weight: bold;
    text-align: center;
}
table td {
    padding: 10px 5px;
    border: 1px #E3E3E3 solid;
    text-align: center;
}

<table>
          <thead>
            <tr>
              <th>名前</th>
              <th>個数</th>
              <th data-override="Score">金額</th></tr>
          </thead>
          <tbody>
            <tr>
              <td>りんご</td>
              <td>3個</td>
              <td data-override="disqualified">300円</td></tr>
            <tr>
              <td>なし</td>
              <td>2000個</td>
              <td>2億円</td></tr>
            <tr>
              <td>すいか</td>
              <td>1個</td>
              <td>500円</td></tr>
            <tr>
              <td>青春</td>
              <td>1回</td>
              <td>プライスレス</td></tr>
          </tbody>
        </table>
        <button id="convert">変換!</button>