diff --git a/htdocs/projet/card.php b/htdocs/projet/card.php
index 6221e4c2b87..91f57056ec3 100644
--- a/htdocs/projet/card.php
+++ b/htdocs/projet/card.php
@@ -507,7 +507,11 @@ if ($action == 'create' && $user->rights->projet->creer)
     // Thirdparty
     if ($conf->societe->enabled)
     {
-        print '<tr><td>'.$langs->trans("ThirdParty").'</td><td class="maxwidthonsmartphone">';
+        print '<tr><td>';
+        print (empty($conf->global->PROJECT_THIRDPARTY_REQUIRED)?'':'<span class="fieldrequired">');
+        print $langs->trans("ThirdParty");
+        print (empty($conf->global->PROJECT_THIRDPARTY_REQUIRED)?'':'</span>');
+        print '</td><td class="maxwidthonsmartphone">';
         $filteronlist='';
         if (! empty($conf->global->PROJECT_FILTER_FOR_THIRDPARTY_LIST)) $filteronlist=$conf->global->PROJECT_FILTER_FOR_THIRDPARTY_LIST;
        	$text=$form->select_thirdparty_list(GETPOST('socid','int'), 'socid', $filteronlist, 'SelectThirdParty', 1, 0, array(), '', 0, 0, 'minwidth300');
@@ -719,7 +723,11 @@ elseif ($object->id > 0)
         // Thirdparty
         if ($conf->societe->enabled)
         {
-            print '<tr><td>'.$langs->trans("ThirdParty").'</td><td>';
+            print '<tr><td>';
+            print (empty($conf->global->PROJECT_THIRDPARTY_REQUIRED)?'':'<span class="fieldrequired">');
+            print $langs->trans("ThirdParty");
+            print (empty($conf->global->PROJECT_THIRDPARTY_REQUIRED)?'':'</span>');
+            print '</td><td>';
     	    $filteronlist='';
     	    if (! empty($conf->global->PROJECT_FILTER_FOR_THIRDPARTY_LIST)) $filteronlist=$conf->global->PROJECT_FILTER_FOR_THIRDPARTY_LIST;
             $text=$form->select_thirdparty_list($object->thirdparty->id, 'socid', $filteronlist, 'None', 1, 0, array(), '', 0, 0, 'minwidth300');
diff --git a/htdocs/projet/class/project.class.php b/htdocs/projet/class/project.class.php
index edd4c6eed12..1afac184b64 100644
--- a/htdocs/projet/class/project.class.php
+++ b/htdocs/projet/class/project.class.php
@@ -139,7 +139,13 @@ class Project extends CommonObject
             dol_syslog(get_class($this)."::create error -1 ref null", LOG_ERR);
             return -1;
         }
-
+        if (! empty($conf->global->PROJECT_THIRDPARTY_REQUIRED) && ! $this->socid > 0)
+        {
+            $this->error = 'ErrorFieldsRequired';
+            dol_syslog(get_class($this)."::create error -1 ref null", LOG_ERR);
+            return -1;
+        }
+        
         $this->db->begin();
 
         $sql = "INSERT INTO " . MAIN_DB_PREFIX . "projet (";