 Robert LamoureuxArsène Lupin / Lieutenant André Laroche | Arsène Lupin / Lieutenant André Laroche |
 Robert DalbanInspector Béchoux of the Judicial Police | Inspector Béchoux of the Judicial Police |
 Alida ValliAurélia Valéano | Aurélia Valéano |
 Jacques DufilhoAlbert, manservant | Albert, manservant |
 Yves RobertLa Ballu | La Ballu |
 Roger DumasIsidore Bautrelet aka 'Véritaz' | Isidore Bautrelet aka 'Véritaz' |
 Hubert de LapparentFrench Consul in Florence | French Consul in Florence |
 Jean BellangerSleeping car employee | Sleeping car employee |
| LLiliane ChenevièreNot listed | Not listed |
 Michel EtcheverryVan Nelden, collector | Van Nelden, collector |
 Jean GallandGeneral | General |
 Gisèle GrandpréMadame du Bois-Lambert | Madame du Bois-Lambert |
 Harold KayHenri | Henri |
 Paul MüllerAttaché of the French consulate in Florence | Attaché of the French consulate in Florence |
 Ginette PigeonAgnès, nurse | Agnès, nurse |
| AAnne ValonNot listed | Not listed |
 Michel VocoretNot listed | Not listed |
 Gérard DarrieuSidekick | Sidekick |
 Pierre Duncan(uncredited) | (uncredited) |
 Gabriel GobinSNCF employee (uncredited) | SNCF employee (uncredited) |
 René HellPrison guard (uncredited) | Prison guard (uncredited) |
 René Lefèvre-Bel(uncredited) | (uncredited) |
 Judith Magre(uncredited) | (uncredited) |
| CClaude Mercutio(uncredited) | (uncredited) |
 Paul PréboistDrunkard of Enghien (uncredited) | Drunkard of Enghien (uncredited) |
 Robert RollisTraveler on the train (uncredited) | Traveler on the train (uncredited) |
 Paul VilléSecretary of the archives (uncredited) | Secretary of the archives (uncredited) |
