PURPOSE: To enable analysis of a cardiogram signal at a high accuracy by arranging a filter adapted to stress a signal component alone of an R wave in an electrocardiogram signal amplified and a threshold value generating section which allows the altering of a level of a threshold value from outside to alter a threshold level for detecting the R wave by a direction from an operator.

CONSTITUTION: An electrocardiograph signal from a person to be inspected is amplified with an input amplifying section 1 and digitized with an A/D conversion part 2 to be inputted into a central processing section 7. The signal amplified with the input amplifying section 1 is converted with a filter section 3 into a signal stressing a signal component alone of an R wave. On the other hand, a signal of a threshold value generating section 5 is compared with an output signal of the filter section 3 by means of an R wave detecting section 4 to detect the R wave. The R wave detecting section 4 outputs a signal to the central processing section 7 and after an analysis, the signal is recorded and displayed according to a direction from an operating section 8.