A printer for executing a print process based on a print job, comprising: an installation portion to which a storage medium storing a print job is detachably installed; an authenticator adapted to authenticate a login of a user who has authority for accessing the storage medium and executing a print process of the print job when authentication is approved; characterised in that it further comprises: a prohibited job memory adapted to store a prohibition information list; a prohibition list register adapted to, when authentication is approved, load job information on the print job from the storage medium and to store the job information in the prohibited job memory as the prohibition information list in a case where a preset time has elapsed from a last operation by the user or a case where the storage medium is still installed in the installation portion at a logoff request by the user; and a controller adapted to, in loading a print job from the storage medium installed in the installation portion, prohibit a print process of the print job loaded from the storage medium when job information of the print job loaded from the storage medium corresponds with the job information contained in the prohibition information list and adapted to start and finish execution of the print process of the print job when the job information of the print job loaded from the storage medium does not correspond with the job information contained in the prohibition information list. an installation portion to which a storage medium storing a print job is detachably installed; an authenticator adapted to authenticate a login of a user who has authority for accessing the storage medium and executing a print process of the print job when authentication is approved; characterised in that it further comprises: a prohibited job memory adapted to store a prohibition information list; a prohibition list register adapted to, when authentication is approved, load job information on the print job from the storage medium and to store the job information in the prohibited job memory as the prohibition information list in a case where a preset time has elapsed from a last operation by the user or a case where the storage medium is still installed in the installation portion at a logoff request by the user; and a controller adapted to, in loading a print job from the storage medium installed in the installation portion, prohibit a print process of the print job loaded from the storage medium when job information of the print job loaded from the storage medium corresponds with the job information contained in the prohibition information list and adapted to start and finish execution of the print process of the print job when the job information of the print job loaded from the storage medium does not correspond with the job information contained in the prohibition information list. a prohibited job memory adapted to store a prohibition information list; a prohibition list register adapted to, when authentication is approved, load job information on the print job from the storage medium and to store the job information in the prohibited job memory as the prohibition information list in a case where a preset time has elapsed from a last operation by the user or a case where the storage medium is still installed in the installation portion at a logoff request by the user; and a controller adapted to, in loading a print job from the storage medium installed in the installation portion, prohibit a print process of the print job loaded from the storage medium when job information of the print job loaded from the storage medium corresponds with the job information contained in the prohibition information list and adapted to start and finish execution of the print process of the print job when the job information of the print job loaded from the storage medium does not correspond with the job information contained in the prohibition information list.