A waste liquid container is detachably mounted on a mounting unit which includes a discharge portion discharging a waste liquid and a projection to which a substrate connection portion is joined. The waste liquid container includes: a containing portion that is able to contain the waste liquid; a connection concave portion that is opened in a mounting direction; a circuit substrate that includes connection terminals electrically connected to the substrate connection portion and is joined to the connection concave portion; and a waste liquid introduction portion that is connected to the discharge portion. In the connection concave portion, one pair of guide portions guiding the projection is formed so that the connection terminals are interposed therebetween in a width direction intersecting the mounting direction. Of the pair of guide portions, one guide portion is disposed between the connection terminals and the waste liquid introduction portion in the width direction.