This paper presents muscle-inspired serial digital actuators, achieving the improvement of the range-to-precision and range-to-voltage performance. We propose a weight-balanced design for the serial actuators with serpentine springs using serial arrangement of digital actuators. We have measured the displacement range, precision, and drive voltage at unit and serial actuation of 1Hz. The serial digital actuators produce a full range displacement of $28.44{pm}0.02{mu}m$, accumulating the unit displacement of $2.8{pm}0.5{mu}m$ at the operating voltage of $4.47{pm}0.07V$. In addition, the serial digital actuators having the displacement precision of $37.94{pm}6.26nm$ do not accumulate the precision of the unit actuators, $36.0{pm}17.7nm$. We experimentally verify that the serial digital actuators achieve the range-to-squared-voltage ratio of $1.423{mu}m/V^2$ and the range-to-precision ratio of 749.6.