Heart disease is caused by a cardiac function which does not work optimally. This illness can be detected by sensing a pulse that is defined as the rhythm of the heartbeat. Some researchers have conducted a study to determine and monitor heart rate. Researches resulted in very expensive and not portable tools. Therefore, this paper examines portable heart rate monitoring with photoplethysmography method and decision tree algorithm. The photoplethysmography method is an optical technique that is cheap and simple that can be used to detect changes in blood volume in the microvascular network. The method modified on the transmitter and receiver sensors. The decision tree algorithm is used to make decisions for one’s pulse form of digital data retrieval heart rate. With the decision tree algorithm obtained a normal heart, Bradycardia, and Tachycardia. The method and algorithm result in a much cheaper tool which can detect heart rate which later is categorized into the normal heart, Bradycardia, or Tachycardia.