Housing includes: insertion part into which a connection target is inserted; a plurality of first grooves provided inside insertion part so as to align along an alignment direction being perpendicular to the insertion direction of the connection target, first contact parts being respectively disposed in first grooves; a plurality of second grooves provided inside insertion part so as to oppose to first grooves, second contact parts being respectively disposed in second grooves; first partition wall partitioning adjacent first contact parts; and second partition wall partitioning adjacent second contact parts. At least one of first partition wall and second partition wall has a height dimension in a direction perpendicular to both the insertion direction and the alignment direction, the height dimension being smaller at least at one end in the alignment direction than at a portion between opposite ends in the alignment direction in order to reduce capacitance between contact parts.