A liquid cartridge is configured to be inserted into a cartridge-attachment section including a casing and a light blocking portion. The casing includes a liquid chamber; a liquid passage extending in a first direction; and a top surface facing upward. The light blocking portion is deformable between a non-deformed state and a deformed state. The light blocking portion, at least in the non-deformed state, is configured to block or attenuate light emitted from the cartridge-attachment section and traveling in a widthwise direction crossing the first direction and a gravitational direction in an upright posture. The light blocking portion in the non-deformed state is configured to be deformed to the deformed state by an external force. The light blocking portion returns to the non-deformed state when the external force is removed from the light blocking portion in the deformed state.