1. An image forming apparatus comprising: an image forming unit that forms an image on a recording material; a cause ascertaining unit that ascertains a cause of a streaked image that is generated in the image that is formed on the recording material by the image forming unit; an outputting unit that outputs information regarding the cause ascertained by the cause ascertaining unit; wherein the image forming unit includes a plurality of members, and wherein the cause ascertaining unit ascertains the cause based on an image formed on the recording material by the image forming unit in which an operation of at least one of the members is stopped, or based on an image formed on the recording material by the image forming unit in which an operation parameter of the at least one of the members is changed.