A roller input device includes a housing, a passive member and an active member. A roller is pivotally disposed inside the housing, and the roller includes an annular tooth portion. The passive member is movably disposed inside the housing, and the passive member includes an abutting portion and a first magnetic module. The active member has a second magnetic module, and the active member is disposed inside the housing and operably moved to a first mode or a second mode to make the first magnetic module and the second magnetic module attract each other or make the first magnetic module and the second magnetic module repel each other to drive the passive member to move relative to the housing to a first position or a second position, such that the abutting portion and the annular tooth portion abut against or separate from each other.