To disclose a biomedical signal processor with a simple configuration and a minimum space capable of confirming an operating condition and a signal collection state of the biomedical signal processor such as an electrocardiograph. As an example of the biomedical signal processor according to the present invention, a Holter electrocardiograph supplies biomedical signals to a light-emitting element (LED) 30 and applies a bias supply voltage from a power supply section 80 to the LED 30. By setting a bias voltage to a voltage so that a level of a minimum supply voltage to the LED 30 becomes a positive potential when electrocardiogram signals are input to an input amplification section 10, the LED 30 turns OFF when power is turned OFF, becomes half-lit when power is turned ON and its luminescence intensity is variable when signals are collected normally, making it possible to easily check a state of the apparatus.