A connector attachable to a board having a principal surface, a recess and a board-side contact portion, wherein: the connector is constructed in a way that, when the connector is attached to the board, the connector is, at least in part, arranged within the recess; the connector comprises an accommodation portion extending in a front-rear direction, also referred as first horizontal direction configured to be able to accommodate a mating connector; wherein an upper-lower direction is perpendicular to the first horizontal direction; the connector comprises at least one contact and a holding member which holds the contact; the contact has a held portion held by the holding member, a support portion extending from the held portion to be resiliently deformable and a contact portion supported by the support portion; the connector is constructed in a way that, when the connector is attached to the board, the contact portion is brought into contact with the board-side contact portion; the holding member has at least one protection portion which protects the contact; the connector is constructed in a way that, when the connector is attached to the board, the protection portion is, at least in part, positioned within the recess; and the holding member has a side surface (161, 163) and a side recess which is formed by walls and recessed inward from the side surface (161, 163); characterized in that at least a part of the walls works as the protection portion; the support portion and the contact portion are positioned within the side recess; and the connector is constructed in a way that the protection portion hides the support portion and the contact portion when seen along the first horizontal direction. the connector is constructed in a way that, when the connector is attached to the board, the connector is, at least in part, arranged within the recess; the connector comprises an accommodation portion extending in a front-rear direction, also referred as first horizontal direction configured to be able to accommodate a mating connector; wherein an upper-lower direction is perpendicular to the first horizontal direction; the connector comprises at least one contact and a holding member which holds the contact; the contact has a held portion held by the holding member, a support portion extending from the held portion to be resiliently deformable and a contact portion supported by the support portion; the connector is constructed in a way that, when the connector is attached to the board, the contact portion is brought into contact with the board-side contact portion; the holding member has at least one protection portion which protects the contact; the connector is constructed in a way that, when the connector is attached to the board, the protection portion is, at least in part, positioned within the recess; and the holding member has a side surface (161, 163) and a side recess which is formed by walls and recessed inward from the side surface (161, 163); characterized in that at least a part of the walls works as the protection portion; the support portion and the contact portion are positioned within the side recess; and the connector is constructed in a way that the protection portion hides the support portion and the contact portion when seen along the first horizontal direction.