kintone on cybozu.com sample code. When Editing record event occurred, u can make some fields uneditable.

kintone_make_field_disabled.js

(function () {
  "use strict";
  
  kintone.events.on('app.record.edit.show', function(event) {
    var record = event.record;
    record['here_is_field_id']['disabled'] = true;
    return event;
  });
})();