Multi-beam light source device and multi-beam light scanning device

A multi-beam scanning device comprising:

• a multi-beam light source device including:
• a light source including:
• a cylindrical package having a side edge portion which extends in a rotational direction about a rotational axis line defined as a first direction;
• a plurality of light emitting units which are disposed in the cylindrical package and configured to emit laser light in the first direction;
• and
• a housing which holds the light source, wherein the housing has a holder that holds the side edge portion of the cylindrical package to be relatively rotatable in the rotational direction, and wherein the holder is formed with at least one opening which exposes the side edge portion of the light source;
• an optical element configured to convert the laser light emitted from the light source into light flux;
• and
• a deflector configured to deflect light, which is converted into the light flux.