function CheckForm(Join){ var chk1=document.Join.U_checkAgreement1.checked; var chk2=document.Join.U_checkAgreement2.checked; if(chk1==""){ alert('약관에동의해 주세요'); return false; } if(chk2==""){ alert('약관에동의해 주세요'); return false; } } <form name=Join action="/" onSubmit="return CheckForm(this)"> <input name="U_checkAgreement1" type="checkbox" value="" id="U_checkAgreement1" class="inputCheck" /> 약관동의 <input name="U_checkAgreement2" type="checkbox" value="" id="U_checkAgreement1" class="inputCheck" /> 약관동의 <input type="image" src="/images/btn_member_join3.gif" border="0" alt="회원가입"> </form>

