Result

jQuery

$('#check').click(function(){
     
    if($(this).prop('checked') == false){
         $('#submit').attr("disabled","disabled");   
    }
    else {
        $('#submit').removeAttr('disabled');
    }
});

html

<input type="checkbox" checked="checked" id="check"><a href="#">利用規約</a>に同意して送信する
<input type="submit" id="submit" value="submit">

via

How do i disable a submit button when checkbox is uncheck?

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