diff --git a/app/assets/javascripts/admin.js b/app/assets/javascripts/admin.js
index 6c2e63536..4b381dbe7 100644
--- a/app/assets/javascripts/admin.js
+++ b/app/assets/javascripts/admin.js
@@ -23,13 +23,13 @@ function destroy_action(){
 }
 
 function on_change_type_de_champ_select (){
-
     $("select.form-control.type_champ").on('change', function(e){
 
         parent = $(this).parent().parent();
 
         parent.removeClass('header_section');
         parent.children(".drop_down_list").removeClass('show_inline');
+        $('.mandatory', parent).show();
 
         switch(this.value){
             case 'header_section':
@@ -38,7 +38,9 @@ function on_change_type_de_champ_select (){
             case 'drop_down_list':
                 parent.children(".drop_down_list").addClass('show_inline');
                 break;
-
+            case 'explication':
+                $('.mandatory', parent).hide();
+                break;
         }
-    })
+    });
 }
diff --git a/app/models/type_de_champ.rb b/app/models/type_de_champ.rb
index 19f263860..64277d606 100644
--- a/app/models/type_de_champ.rb
+++ b/app/models/type_de_champ.rb
@@ -30,7 +30,7 @@ class TypeDeChamp < ActiveRecord::Base
   validates :libelle, presence: true, allow_blank: false, allow_nil: false
   validates :type_champ, presence: true, allow_blank: false, allow_nil: false
 
-  before_validation :change_header_section_mandatory
+  before_validation :check_mandatory
 
   def self.type_de_champs_list_fr
     type_champs.map { |champ| [I18n.t("activerecord.attributes.type_de_champ.type_champs.#{champ.last}"), champ.first] }
@@ -40,8 +40,8 @@ class TypeDeChamp < ActiveRecord::Base
     !(type_champ == 'textarea' || type_champ == 'header_section')
   end
 
-  def change_header_section_mandatory
-    self.mandatory = false if self.type_champ == 'header_section'
+  def check_mandatory
+    self.mandatory = false if %w(header_section explication).include?(self.type_champ)
     true
   end
 end
diff --git a/app/views/admin/types_de_champ/_fields.html.haml b/app/views/admin/types_de_champ/_fields.html.haml
index 649be960e..37da7585b 100644
--- a/app/views/admin/types_de_champ/_fields.html.haml
+++ b/app/views/admin/types_de_champ/_fields.html.haml
@@ -1,27 +1,29 @@
 = f.fields_for @types_de_champ_facade.fields_for_var, types_de_champ, remote: true do |ff|
-  .form-inline{class:"#{ff.object.object.type_champ == 'header_section' ? 'header_section' : ''}"}
+  .form-inline{ class: (ff.object.object.type_champ == 'header_section' ? 'header_section' : '') }
     .form-group.libelle
       %h4 Libellé
       = ff.text_field :libelle, class: 'form-control libelle', placeholder: 'Libellé'
 
     .form-group.type
       %h4 Type
-      = ff.select :type_champ, TypeDeChamp.type_de_champs_list_fr, {}, {class: 'form-control type_champ'}
+      = ff.select :type_champ, TypeDeChamp.type_de_champs_list_fr, {}, { class: 'form-control type_champ' }
 
     .form-group.description
       %h4 Description
-      = ff.text_area :description, class: 'form-control description', placeholder: 'Description', rows: 2
+      = ff.text_area :description, class: 'form-control description', placeholder: 'Description', rows: 3
 
-    .form-group.drop_down_list{class:"#{ff.object.object.type_champ == 'drop_down_list' ? 'show_inline' : ''}",style:'margin-right: 5px'}
+    .form-group.drop_down_list{ class: (ff.object.object.type_champ == 'drop_down_list' ? 'show_inline' : ''), style: 'margin-right: 5px' }
       %h4 Liste déroulante
       = ff.fields_for :drop_down_list_attributes, ff.object.object.drop_down_list do |fff|
         = fff.text_area :value, class: 'form-control drop_down_list', placeholder: "Ecrire une valeur par ligne.\nEcrire --valeur-- pour un séparateur.", rows: 3, cols: 30
         = fff.hidden_field :id
-    - unless ff.object.object.class == TypeDeChampPrivate
-      .form-group.mandatory
-        %h4 Obligatoire ?
-        .center
-          = ff.check_box :mandatory, placeholder: 'Obligatoire ?'
+
+
+    - hide_mandatory = (ff.object.object.class == TypeDeChampPrivate || ff.object.object.type_champ == 'explication')
+    .form-group.mandatory{ style: hide_mandatory ? 'visibility: hidden;' : '' }
+      %h4 Obligatoire ?
+      .center
+        = ff.check_box :mandatory, placeholder: 'Obligatoire ?'
 
     .form-group
       = ff.hidden_field :order_place, value: ff.index