Electrocardiography is one of the most important tools used for the diagnosis of heart diseases. The heart is a vital organ of the body that forms a pump to circulate blood throughout blood vessels in the body. Electrocardiogram (ECG) signal of a person symbolizes the heart' s electrical activity recorded by placing electrodes on his body surface. ECG signal also provides essential information about the proper functioning of the heart and rate & regularity of the heart beats. There are certain irregularities present in ECG signal due to abnormal activity of the heart which are termed as Arrhythmia. Hence it becomes imperative to properly analyze the ECG signal. However, it is very difficult to analyze ECG signal being of non-stationary nature. A lot of research has been done for analysis and detection of ECG signal. Nevertheless, Wavelet Transform analysis proves to be better method than other methods as it breaks a signal into shifted and scaled version of original wavelet and consumes less computation time. In this study, a number of ECG signal samples varying in age and gender have been analyzed; and different cardiac diseases are detected through Wavelet Transform.