function login_chk() {
  var form = document.frm_login;
  var msg = "";

  form.tel.value = form.tel.value.replace(/^[\s　]+|[\s　]+$/g, "");
  form.pass.value = form.pass.value.replace(/^[\s　]+|[\s　]+$/g, "");

  if (form.tel.value === "" || form.tel.value.match(/[^0-9]/g)) {
    msg += "ログインIDの入力が正しくありません。\n";
  }

  if (form.pass.value === "" || form.pass.value.match(/[^0-9a-zA-Z_]+/)) {
    msg += "パスワードの入力が正しくありません。\n";
  }

  if (msg !== "") {
    alert(msg);
    return false;
  }

  var xmlhttp = window.XMLHttpRequest
    ? new XMLHttpRequest()
    : new ActiveXObject("Microsoft.XMLHTTP");

  xmlhttp.onreadystatechange = function () {
    if (xmlhttp.readyState !== 4 || xmlhttp.status !== 200) {
      return;
    }

    if (xmlhttp.responseText.replace(/^\s+|\s+$/g, "") === "") {
      form.submit();
    } else {
      document.getElementById("errormsg").innerHTML = xmlhttp.responseText;
    }
  };

  var params = [
    Date.now(),
    "tel=" + encodeURIComponent(form.tel.value),
    "sex_sel=" + encodeURIComponent(form.sex_sel.value),
    "pass=" + encodeURIComponent(form.pass.value),
    "eid=" + encodeURIComponent(form.eid.value)
  ];

  xmlhttp.open("GET", "login_ajax.php?" + params.join("&"), true);
  xmlhttp.send();
  return false;
}