Metal-based mounting board and member provided with metal-based mounting board

A metal-based mounting board according to the present invention includes: a metal-based circuit board including a metal substrate having a first surface and a second surface opposite to the first surface, an insulating film provided on the first surface of the metal substrate and a metal film provided on the insulating film; and an electronic component provided on the metal film of the metal-based circuit board, wherein in the case where within the metal substrate, a region which overlaps with a collection of a plurality of lines each having an angle of 45 DEG or less with respect to a normal line of the metal-based mounting board, the lines each passing through a surface of the electronic component facing the metal film, is defined as a first region, and a region other than the first region is defined as a second region, a groove is provided within the second region, but is not provided within the first region.