HTML

<input type="checkbox" id="checkBox_01">
<input type="checkbox" id="checkBox_02">
<input type="button" value="다음단계" id="nextStep">

<!--/js-->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>

JAVASCRIPT

$(document).ready(function(){
    $('#nextStep').click(function(){
        if($('#checkBox_01').prop('checked') == false || $('#checkBox_02').prop('checked') == false){
            alert('필수 약관에 동의 하셔야 합니다.');
        }else{
            $(location).attr('href','https://www.naver.com/');
        }
    });
});