A resin multilayer board includes an insulating substrate including a first main surface and mounting electrodes only on the first main surface. The insulating substrate includes first and second resin layers that are laminated. The Young's modulus of the second resin layers is higher than that of the first resin layers. The first and second resin layers are arranged in a distributed manner along a lamination direction of the first and second resin layers. The insulating substrate includes a first and second portions that are two equally divided portions of the insulating substrate in the lamination direction and are respectively positioned closer to the first main surface and farther from the first main surface, and a volume ratio of the second resin layers in the first portion is higher than a volume ratio of the second resin layers in the second portion.