The authors have been working to establish an anti-icer spreading support technology that is inexpensive, does not depend on the operator’s skill level, and enables reliable and safe operation by a one-person work vehicle. Therefore, in the early studies, a series of experiments on the test track were performed. The benefits and problems that the spreading support brings to the operators by examining their mental workload as a function of the presence or absence and type of support were extracted. Based on the experiment results, for the winter of 2020, an Anti-icing Agent Spreading Support System (AIS3) was developed. The AIS3 supports the operators in their tasks, including issuing work instructions, judging road surface conditions, and operating the spreader. Then, the effectiveness of the AIS3 on actual roads was evaluated. As results, by using the voice command function and the automatic spreading function, which are the main components of AIS3, the burden on operators and misjudgments were able to be significantly reduced even on real roads. So, spreading operations were able to be performed as accurately and safely on the real roads as they were on the test track were clarified. Especially the accuracy of the automatic spreading function of AIS3 was extremely high.