We report a simple and easy method for the integration of planar-type single-electron transistors (SETs). This method is based on electromigration induced by a field emission current, which is so-called "activation". The integration of two SETs was achieved by performing the activation to the series-connected initial nanogaps. In both simultaneously activated devices, current-voltage (I-D-V-D) curves displayed Coulomb blockade properties, and Coulomb blockade voltage was also obviously modulated by the gate voltage at 16K. Moreover, the charging energy of both SETs was well controlled by the preset current in the activation. (C) 2011 Elsevier B.V. All rights reserved.