A catheter includes an elongate member configured to have a longitudinal axis and formed of a thermoplastic resin; an elongate guide wire holder section configured to include a cavity into which a guide wire is insertable at an interior of the elongate member; a cross-linked section configured to have a high cross-linked section and a low cross-linked section which is adjacent to the high cross-linked section in a radial direction of the elongate member and in which the cross-linking degree is relatively lower than that of the high cross-linked section; and an opening section configured to communicate with the cavity of the guide wire holder and an outer circumferential surface of the guide wire holder in the low cross-linked section of the cross-linked section and formed in a slit shape along the longitudinal axis of the guide wire holder.