Electrocardiographic (ECG) equipment plays a vital role for diagnosis of cardiac disease. However, the cost of this equipment is huge and the operation is too much complex which cannot offer better services to a large population in developing countries like Bangladesh. In this paper, we have designed and implemented a low cost portable single channel ECG monitoring system using smartphone having android operating system and Arduino. This manuscript also demonstrates the use of Android smartphone for processing and visualizing ECG signal. Our designed system is battery powered and it gives wireless feature. This system can also be used with desktop computer or laptop having either Windows, Linux or Mac OS. For this purpose a software is developed. An Android application is developed using Processing IDE, which requires Android version 2.3 and API level of 10. This application does not need USB host API. For this reason, around 98% Android smartphone in the market can be used for this system.