Resin sheet and resin multilayer substrate

A resin sheet comprising:

• one or more kinds of resin materials;
• and
• a liquid crystal polymer,
• wherein the one or more kinds of resin materials is a norbornene-based polymer containing at least one of repeating units represented by the following formula (1):
• wherein
• X represents O, —CH2— or —CH2—CH2—;
• each of substituents R1, R2, R3, and R4 represents a group containing a group selected from hydrogen, a linear or branched organic group, or a derivative in which a part of these linear or branched organic groups is substituted with a halogen or a nitrile group;
• m is an integer of 10 to 10000;
• and
• n1 is an integer of 0 to 5,
• a highest melting point among melting points of the one or more kinds of resin materials is lower than a melting point of the liquid crystal polymer by 30° C. or more,
• a weight of the liquid crystal polymer is less than a total weight of the one or more kinds of resin materials, and
• the resin sheet has a thermal expansion coefficient in a plane direction smaller than a thermal expansion coefficient in the plane direction of a comparative resin sheet containing the one or more kinds of resin materials and not containing the liquid crystal polymer.