diff --git a/addons/calendar/models/calendar_attendee.py b/addons/calendar/models/calendar_attendee.py
index 0f9a98c100f..afc89801a04 100644
--- a/addons/calendar/models/calendar_attendee.py
+++ b/addons/calendar/models/calendar_attendee.py
@@ -33,7 +33,7 @@ class Attendee(models.Model):
     event_id = fields.Many2one('calendar.event', 'Meeting linked', required=True, ondelete='cascade')
     recurrence_id = fields.Many2one('calendar.recurrence', related='event_id.recurrence_id')
     # attendee
-    partner_id = fields.Many2one('res.partner', 'Attendee', required=True, readonly=True)
+    partner_id = fields.Many2one('res.partner', 'Attendee', required=True, readonly=True, ondelete='cascade')
     email = fields.Char('Email', related='partner_id.email')
     phone = fields.Char('Phone', related='partner_id.phone')
     common_name = fields.Char('Common name', compute='_compute_common_name', store=True)