Stethoscope is a medical instrument acoustics for examine sound in body’s sound. The instrument usually using to listen heartbeat, respiration and blood vessel in vena and artery. The instrument also using by mechanical for isolation specific sound from diagnosis machine. Monitoring object stethoscope is heart sound or lung sound.The technic is called ausculultation. Trouble with using heart and lung auscultation by stethoscope is noise area, low sensitivity, amplitude, low frequency,and equal relative sound system. It motivation writer for make the instrument “Electronic Stethoscope With Heartbeat Calculation Per Minute Based Microcontroller” is a stethoscope using by diagnostic medical instrument with sound output heartbeat that amplification by an op-amp module an displaying heartbeat result for a minute by LCD 2x16. Module in the instrument composed by amplifiers module for amplification heartbeat input then output sound can listen by speaker. Patient heartbeat calculating for 15 seconds then the result procceced by microcontroller AT Mega 8535 for times four and finally the last result is patient heartbeat per minute. As compared from calculation heartbeat per minute, so in research using Sp02 portable that calibrate to know accuration the instrument made by writer.