Unbalance exciter modular system for an unbalance exciter for a vibratory plate for ground compaction, comprising: - two different designs of rotatably mounted unbalance shafts, on which an unbalance mass (5, 13) is provided in each case in order to generate an unbalance, wherein the two different designs are provided for two different drive types; - an exciter housing which at least partly surrounds the unbalance shaft; and comprising - at least two bearing devices for the rotatable mounting of the unbalance shaft in the exciter housing, wherein the unbalance shaft has two bearing seats, on which bearing devices mount the unbalance shaft; wherein - the exciter housing has a central part; - the exciter housing has two end parts which are arranged at ends of the central part; - the central part has a hollow-cylindrical recess, in which one bearing point is provided for each of the bearing devices; - the central part is designed to optionally accommodate one of the unbalance shafts for one of the two different drive types, namely a first drive type and a second drive type; - the central part is identical for both drive types, whereas the respective unbalance shafts are different for the two drive types; - the modular system is designed for an unbalance exciter according to the first drive type, in which the unbalance exciter can be driven by means of a drive device provided outside the exciter housing of the unbalance exciter; and wherein - the modular system is designed for an unbalance exciter according to the second drive type, in which the unbalance exciter can be driven by means of a drive device provided inside the exciter housing of the unbalance exciter. - two different designs of rotatably mounted unbalance shafts, on which an unbalance mass (5, 13) is provided in each case in order to generate an unbalance, wherein the two different designs are provided for two different drive types; - an exciter housing which at least partly surrounds the unbalance shaft; and comprising - at least two bearing devices for the rotatable mounting of the unbalance shaft in the exciter housing, wherein the unbalance shaft has two bearing seats, on which bearing devices mount the unbalance shaft; wherein - the exciter housing has a central part; - the exciter housing has two end parts which are arranged at ends of the central part; - the central part has a hollow-cylindrical recess, in which one bearing point is provided for each of the bearing devices; - the central part is designed to optionally accommodate one of the unbalance shafts for one of the two different drive types, namely a first drive type and a second drive type; - the central part is identical for both drive types, whereas the respective unbalance shafts are different for the two drive types; - the modular system is designed for an unbalance exciter according to the first drive type, in which the unbalance exciter can be driven by means of a drive device provided outside the exciter housing of the unbalance exciter; and wherein - the modular system is designed for an unbalance exciter according to the second drive type, in which the unbalance exciter can be driven by means of a drive device provided inside the exciter housing of the unbalance exciter.