An image forming apparatus comprising a plurality of image forming units (10W, 10Y, 10C, 10M, 10K); the plurality of image forming units (10W, 10Y, 10C, 10M, 10K) including: a first image forming unit that uses a first developer having first charging characteristics; and a second image forming unit that uses a second developer having second charging characteristics differing from the first charging characteristics; the first image forming unit including: a first image carrier; a first developer carrier that is applied with a first developing voltage and develops a latent image on the first image carrier with the first developer; and a first layer-forming member that is applied with a first layer-forming voltage having the same polarity as polarity of the first developing voltage and is disposed to face the first developer carrier; the second image forming unit including: a second image carrier; a second developer carrier that is applied with a second developing voltage and develops a latent image on the second image carrier with the second developer; and a second layer-forming member that is applied with a second layer-forming voltage having the same polarity as polarity of the second developing voltage and is disposed to face the second developer carrier; wherein: during image forming operation, an absolute value of the first layer-forming voltage is smaller than an absolute value of the first developing voltage; and an absolute value of the second layer-forming voltage is greater than an absolute value of the second developing voltage. a first image forming unit that uses a first developer having first charging characteristics; and a second image forming unit that uses a second developer having second charging characteristics differing from the first charging characteristics; the first image forming unit including: a first image carrier; a first developer carrier that is applied with a first developing voltage and develops a latent image on the first image carrier with the first developer; and a first layer-forming member that is applied with a first layer-forming voltage having the same polarity as polarity of the first developing voltage and is disposed to face the first developer carrier; a first image carrier; a first developer carrier that is applied with a first developing voltage and develops a latent image on the first image carrier with the first developer; and a first layer-forming member that is applied with a first layer-forming voltage having the same polarity as polarity of the first developing voltage and is disposed to face the first developer carrier; the second image forming unit including: a second image carrier; a second developer carrier that is applied with a second developing voltage and develops a latent image on the second image carrier with the second developer; and a second layer-forming member that is applied with a second layer-forming voltage having the same polarity as polarity of the second developing voltage and is disposed to face the second developer carrier; wherein: during image forming operation, an absolute value of the first layer-forming voltage is smaller than an absolute value of the first developing voltage; and an absolute value of the second layer-forming voltage is greater than an absolute value of the second developing voltage. a second image carrier; a second developer carrier that is applied with a second developing voltage and develops a latent image on the second image carrier with the second developer; and a second layer-forming member that is applied with a second layer-forming voltage having the same polarity as polarity of the second developing voltage and is disposed to face the second developer carrier; wherein: during image forming operation, an absolute value of the first layer-forming voltage is smaller than an absolute value of the first developing voltage; and an absolute value of the second layer-forming voltage is greater than an absolute value of the second developing voltage. during image forming operation, an absolute value of the first layer-forming voltage is smaller than an absolute value of the first developing voltage; and an absolute value of the second layer-forming voltage is greater than an absolute value of the second developing voltage.