A biological signal measuring device that includes a light emitting unit that includes at least a first light emitting element and a second light emitting element that irradiate a biological surface, and a light receiving unit that includes at least one light receiving element that receives light scattered in a living body by light emitted from the light emitting unit, and outputs biological information that is a light intensity signal measured by the light receiving element. The biological signal measuring device is capable of performing both pulse measurement and blood flow measurement with high accuracy.