Edit in JSFiddle

jQuery(function(){

    jQuery('#formdayo > button').click(function(){
        
        var input = jQuery("#formdayo").find("input");
        var flg = "";
        jQuery.each(input,function(i){
            if(jQuery(input[i]).prop("checked")) { flg = jQuery(input[i]).prop("checked"); } 
        });
        if(!flg) { alert("hoge-"); return false; }
        
    });
    

});
<form id="formdayo" action="#" method="post">
    <input type="checkbox" value="1">a
    <input type="checkbox" value="2">b
    <input type="checkbox" value="3">c
    <input type="checkbox" value="4">d
    <input type="checkbox" value="5">e
    <button>abesi</button>
 </form>