Several future Higgs factories are planned for the precision Higgs physics to search for the new physics. The highly granular calorimeters play a crucial role on the precision Higgs measurement. The highly granular Sc-ECAL is based on a scintillator strip readout by a SiPM to realize the 5 mm × 5 mm cell size by aligning the strips orthogonally in x–y configuration. In order to demonstrate the performance of the Sc-ECAL and the scalability to the full-scale detector, the technological prototype has been developed with full 30 layers. The per-channel calibrations and performance demonstration are successfully done by the long-term commissioning tests with LED and cosmic-ray. This article describes the results of the commissioning tests where excellent performance of the prototype has been successfully demonstrated.