Heartbeat counter with finger sensor is a device used to count the number of heartbeats in units of BPM (Beat Per Minute). Measurement of heart rate is important for knowing the number of our heartbeats then we will know if we have a normal heart rate, bradycardia (BPM below normal) or tachycardia (BPM above normal). The device works is by way of finger sensors mounted on the finger emits infrared light that passes through the fingers, and the light is captured by a photodiode. Because of the influence of blood flow then the resulting signal. Then the signal obtained by the sensor is forwarded to the amplifier circuit, to provide reinforcement. Furthermore filtered to remove noise signals obtained by the heart rate signal. Then forwarded to the monostable circuit that functions convert the analog voltage TTL voltage of 0 V and 5 V, intended to be at the counter by the microcontroller which is then displayed on the display. Results for the normal adult heart rate is 60-100 BPM, above 100 BPM tachycardia and bradycardia below 60 BPM. In testing tool, the authors used an experimental method that periodic testing by comparing the results use comparison to similar tools in order to know their accuracy. Based testing tools, the result that a counter heartbeat tachycardia and bradycardia accompanied diagnosis is working well and has a small error value is 0.72882%.