Thermal bonding sheet and thermal bonding sheet with dicing tape

Provided are a thermal bonding sheet capable of suppressing inhibition of sintering of sinterable metallic particles by an organic component, thereby imparting sufficient bonding reliability to a power semiconductor device, and a thermal bonding sheet with a dicing tape having the thermal bonding sheet. A thermal bonding sheet has a precursor layer that is to become a sintered layer by heating, and the precursor layer includes sinterable metallic particles and an organic component, the precursor layer has a phase separation structure that is a sea-island structure or a co-continuous structure, and in a SEM surface observation image on at least one surface of the precursor layer, a maximum value among each diameter of the largest inscribed circle for a region occupied by each phase of the phase separation structure is 1 μm or more and 50 μm or less.