A laser scanning unit includes a first light source, a second light source, a scanning portion, a light detection portion, a timing control portion, and a light source control portion. The scanning portion is configured to cause light emitted from the first light source and the second light source to be scanned. The light detection portion is configured to detect the light that is scanned by the scanning portion. The timing control portion is configured to control a timing of writing an electrostatic latent image according to a timing of light detection by the light detection portion. The light source control portion is configured to: cause the light detected by the light detection portion to be emitted from the first light source in the first mode; and cause the light detected by the light detection portion to be emitted from the second light source in the second mode.