A noninvasive blood component measuring device configured so as to resolve the variance of measuring results depend on the fixing position to the living body. Concretely, a non-invasive blood component measuring device comprising a light source section for illuminating a living body which includes a blood vessel, an imaging section for imaging the living body illuminated by the light source, and a controller is disclosed. The controller includes a memory under control of a processor. The memory stores instructions enabling the processor to carry out following operations: calculating a blood component concentration based on a blood vessel in a living body image obtained by the imaging section imaging a living body; determining the position of the blood vessel in the living body image; preparing at least a first luminance distribution which is distributed along the blood vessel based on the position of the blood vessel; obtaining an index which reflects the amount of blood contained in the peripheral tissue of the blood vessel based on the first luminance distribution; and correcting the blood component concentration based on the index. Non-invasive blood component measuring method and a computer program product capable of achieving above mentioned function are also disclosed.