An image forming apparatus comprising: a plurality of image carriers (7Y, 7C, 7M, 7K) configured to carry a toner image; an intermediate transfer body configured to come into contact with a plurality of the image carriers (7Y, 7C, 7M, 7K); a plurality of primary transfer members (12Y, 12C, 12M, 12K) configured to primarily transfer the toner image on a plurality of the image carriers (7Y, 7C, 7M, 7K) to the intermediate transfer body; a secondary transfer member configured to secondarily transfer the toner image on the intermediate transfer body to a recording medium; and a first guide member arranged at an upstream side of the secondary transfer member in a conveying direction of the recording medium and configured to guide the recording medium along the conveying direction, characterized in that the image forming apparatus further comprises a controller configured to control both of a primary transfer bias applied to a plurality of the primary transfer members (12Y, 12C, 12M, 12K) when the toner image on a plurality of the image carriers (7Y, 7C, 7M, 7K) is primarily transferred to the intermediate transfer body and a secondary transfer bias applied to the secondary transfer member when the toner image on the intermediate transfer body is secondarily transferred to the recording medium, wherein a plurality of the primary transfer members (12Y, 12C, 12M, 12K) include: an upstream side primary transfer member (12Y, 12C, 12M); and a downstream side primary transfer member arranged at a downstream side of the upstream side primary transfer member (12Y, 12C, 12M) in a running direction of the intermediate transfer body, and the controller makes an absolute value of the primary transfer bias applied to the downstream side primary transfer member larger than an absolute value of the primary transfer bias applied to the upstream side primary transfer member (12Y, 12C, 12M), and the controller lowers an absolute value of the secondary transfer bias when an upstream end part of the recording medium in the conveying direction separates from the first guide member. a plurality of image carriers (7Y, 7C, 7M, 7K) configured to carry a toner image; an intermediate transfer body configured to come into contact with a plurality of the image carriers (7Y, 7C, 7M, 7K); a plurality of primary transfer members (12Y, 12C, 12M, 12K) configured to primarily transfer the toner image on a plurality of the image carriers (7Y, 7C, 7M, 7K) to the intermediate transfer body; a secondary transfer member configured to secondarily transfer the toner image on the intermediate transfer body to a recording medium; and a first guide member arranged at an upstream side of the secondary transfer member in a conveying direction of the recording medium and configured to guide the recording medium along the conveying direction, characterized in that the image forming apparatus further comprises a controller configured to control both of a primary transfer bias applied to a plurality of the primary transfer members (12Y, 12C, 12M, 12K) when the toner image on a plurality of the image carriers (7Y, 7C, 7M, 7K) is primarily transferred to the intermediate transfer body and a secondary transfer bias applied to the secondary transfer member when the toner image on the intermediate transfer body is secondarily transferred to the recording medium, wherein a plurality of the primary transfer members (12Y, 12C, 12M, 12K) include: an upstream side primary transfer member (12Y, 12C, 12M); and a downstream side primary transfer member arranged at a downstream side of the upstream side primary transfer member (12Y, 12C, 12M) in a running direction of the intermediate transfer body, and the controller makes an absolute value of the primary transfer bias applied to the downstream side primary transfer member larger than an absolute value of the primary transfer bias applied to the upstream side primary transfer member (12Y, 12C, 12M), and the controller lowers an absolute value of the secondary transfer bias when an upstream end part of the recording medium in the conveying direction separates from the first guide member. an upstream side primary transfer member (12Y, 12C, 12M); and a downstream side primary transfer member arranged at a downstream side of the upstream side primary transfer member (12Y, 12C, 12M) in a running direction of the intermediate transfer body, and the controller makes an absolute value of the primary transfer bias applied to the downstream side primary transfer member larger than an absolute value of the primary transfer bias applied to the upstream side primary transfer member (12Y, 12C, 12M), and the controller lowers an absolute value of the secondary transfer bias when an upstream end part of the recording medium in the conveying direction separates from the first guide member.