MVC4 Checkbox ensure check at least one?

i'm implementing a checkbox question for let user to choose. However, if admin set the question mandatory to true, the checkbox must select at least 1 to submit, else a message will prompt user to select. I was try added the 'required = "required" ' but it need to check all checkbox just can submit :(

Is it need javascript or jquery to do such validation?

My View:

for (int x = 0; x < Model[i].Choice_SubQuestion.Count(); x++)
     {
         if (Model[i].Mandatory == true)
        {
           // Need to check all only can submit :(                                 
              <input type="checkbox" name="[@i].MultiAnswer[@x]" value="@Model[i].Choice_SubQuestion[x]" required="required"/>
               @Html.HiddenFor(m=>m[i].MultiAnswer[x])
         }
           else
        {
               <input type="checkbox" name="[@i].MultiAnswer[@x]" value="@Model[i].Choice_SubQuestion[x]" />
               @Html.HiddenFor(m => m[i].MultiAnswer[x])
        }

               @Html.LabelFor(m => m[i].MultiAnswer[x], Model[i].Choice_SubQuestion[x].ToString(), new { @class = "questionlist1" })
          <br />

          }