A long-term electricity demand forecasting on the West Kalimantan electricity system using the Simple-E program (from Japan) has been researched, with the study period of 2021 - 2050. Projection of electricity demand growth is conducted by using 3 scenarios, namely: Basic Scenario (Business as Usual (BaU)) where this scenario uses the econometric regression analysis methods; Industrialization Scenario where this scenario uses Basic Scenario (BaU) with added in the plan for the development of industries in West Kalimantan; and Prosperity Scenario where it takes into account the electricity consumption targets per capita in National Energy Policy (Kebijakan Energi Nasional, KEN). The result of the Basic Scenario for electricity demand projection in 2021 is predicted to reach around 3.02 TWh and projected to increase to reach around 15 TWh in 2050. Meanwhile, under Industrialization Scenario, the Basic Scenario (BaU) projection results are injected or added with the electricity demand from industrial and business sectors planned to be developed in West Kalimantan. The projection of electricity demand based on the Industrialization Scenario in 2021 is predicted to reach around 3.02 TWh and projected to increase to reach around 18.7 TWh in 2050. The Prosperity Scenario considers the electricity consumption targets per capita stated in the Energy National Policy (KEN). KEN mandates the electricity consumption per capita for Indonesia of 2,500 kWh/capita in 2025 and 7,000 kWh/capita in 2050. Based on this consideration, the Prosperity Scenario projection of electrical energy demand shows that it rises from initially at around 3.86 TWh in 2021 to reach around 30.1 TWh in 2050. Based on that three scenarios, the projection of electrical energy demand using the Prosperity Scenario is higher than the BaU and Industrialization scenarios. Using the Prosperity Scenario, electrical energy demand in 2050 also reaches twice based on BaU Scenario. This result is due to considering the electricity consumption target per capita, which is relatively high following the target in KEN. Under Industrialization Scenario, the injection of electrical energy demand in the industrial sector causes a jump in electrical energy demand in 2025, exceeding the Prosperity Scenario caused by the presence of some industrial zones targeted to start operation in that year.@en