Suspension board with circuit and producing method thereof

A suspension board with circuit includes a metal supporting board having a support opening portion, a base insulating layer disposed at one side of the metal supporting board, and a conductive layer disposed at one side of the base insulating layer and including a plurality of terminal portions overlapped with the support opening portion and disposed at spaced intervals to each other. The base insulating layer includes a plurality of base opening portions that are disposed between the plurality of terminal portions in an arrangement direction, a plurality of thick portions that are overlapped with each of end portions of the plurality of terminal portions in a direction orthogonal to both directions of the thickness direction and the arrangement direction, and a plurality of thin portions that are disposed along edge portions of the plurality of base opening portions between the plurality of thick portions and are thinner than the plurality of thick portions.