1. An image forming apparatus comprising: an image forming portion configured to form an image; a correcting means configured to form a toner image for detection by using the image forming portion and to perform correction of image forming conditions based on the toner image for detection; a vibration detecting unit configured to detect a vibration of the image forming apparatus; and an executing means configured to automatically execute correction of image forming conditions by using the correcting means if the vibration detecting unit detects a vibration at or above a predetermined vibration level.