Uncaught ReferenceError: $ is not defined

<script>
    setInterval(function () {
        $.ajax({
            type: 'POST',
            url: 'inc/engine.php',
            data: {
                type: 'updatebalance',
                sid: Cookies.get('sid')
            },
            success: function (data) {
                var obj = jQuery.parseJSON(data);
                if (obj.success == 'success') {
                    updateBalance(obj.balance, obj.new_balance);
                }
            }
        });
    }, 3000);
    setInterval(function () {
        $.ajax({
            type: 'POST',
            url: 'inc/engine.php',
            data: {
                type: 'updateout',
                sid: Cookies.get('sid')
            },
            success: function (data) {
                var obj = jQuery.parseJSON(data);
                if (obj.success == 'success') {
                    $('#withdrawT').html(obj.upd_bd);
                }
            }
        });
    }, 1000);
</script>