电动自行车（motorized bicycle / electric bicycle）俗称电动车或电瓶车、电动脚踏车，是一种以蓄电池为主要能源的交通工具，外观与自行车或摩托车相似，属摩托化自行车的一种，部分车种还带有脚踏板、链条，可以用人力作为辅助动力（称为电动辅助自行车）。

在中国大陆，根据1999年《电动自行车通用技术条件》的规定：电动自行车归为助动车，时速规定不得超过20公里，整车重量不得超过40公斤，是非机动车的一种。

在**，电动自行车指指经过型式审验合格，以电力为动力来源，最高时速为25公里，且不含电池车重在四十公斤以下之二轮车辆，具备免考驾照、免挂车牌、免牌照税与燃料税、不强制戴安全帽、不排放污染、低噪音、电费成本低廉等。

An electric bicycle, also known as an e-bike or booster bike, is a bicycle with an integrated electric motor which can be used for propulsion. There are a great variety of e-bikes available worldwide, from e-bikes that only have a small motor to assist the rider's pedal-power (i.e., pedelecs) to somewhat more powerful e-bikes which tend closer to moped-style functionality: all, however, retain the ability to be pedalled by the rider and are therefore not electric motorcycles. E-bikes use rechargeable batteries and the lighter varieties can travel up to 25 to 32 km/h (16 to 20 mph), depending on the laws of the country in which they are sold, while the more high-powered varieties can often do in excess of 45 km/h (28 mph). In some markets, such as Germany, they are gaining in popularity and taking some market share away from conventional bicycles, while in others, such as China, they are replacing fossil fuel-powered mopeds and small motorcycles.