1. 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; a controller, including a memory under control of a processor, the memory storing instructions enabling the processor to carry out operations, comprising: 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.