There is provided a charging technique in which the generation of ozone is suppressed and charging efficiency can be improved. A charging device includes a contact unit configured to include a magnetic brush coming in contact with a body to be charged, the contact unit including, as a magnetic particle forming the magnetic brush, the magnetic particle containing at least a particle having a negative electronegativity, and a voltage application unit configured to negatively charge the body to be charged by applying a specified bias voltage through the magnetic brush in the contact unit to the body to be charged.