A liquid cartridge (30, 230, 330, 430) configured to be inserted into a cartridge-attachment section (110, 210) in an insertion direction crossing a gravitational direction and accommodated in the cartridge-attachment section in an upright posture, the directions up, down, front, rear, left, and right defined for the liquid cartridge in its upright position, the liquid cartridge comprising: a casing (31, 331) comprising: a liquid chamber (32, 33, 332) storing liquid therein; a liquid passage (35, 335) extending from the liquid chamber (32, 33, 332) in the insertion direction; a front wall provided with the liquid passage (35, 335); a rear wall positioned away from the front wall in the insertion direction, the liquid chamber (32, 33, 332) being positioned between the front wall and the rear wall in the insertion direction; a top wall (39, 339) positioned between the front wall and the rear wall in the insertion direction; and a bottom wall positioned between the front wall and the rear wall in the insertion direction and away from the top wall (39, 339) in the gravitational direction, the liquid chamber (32, 33, 332) being positioned between the top wall (39, 339) and the bottom wall in the gravitational direction; and a lever (67, 267) supported by the casing (31, 331) and pivotable about a pivot axis between a first position and a second position, the lever comprising: a light-blocking portion (67A, 267A) configured to block or attenuate light traveling in a widthwise direction crossing the insertion direction and the gravitational direction, the light-blocking portion (67A, 267A) being positioned lower at the second position than at the first position; and a force-receiving portion (67C, 267D) positioned closer to the front wall than the light-blocking portion (67A, 267A) is to the front wall in the insertion direction, the pivot axis being positioned frontward of the light-blocking portion (67A, 267A) and rearward of the force-receiving portion (67C, 267D) in the insertion direction, characterized in that the lever (67, 267) is configured to pivot from the second position to the first position upon application of an external force to the force-receiving portion. a casing (31, 331) comprising: a liquid chamber (32, 33, 332) storing liquid therein; a liquid passage (35, 335) extending from the liquid chamber (32, 33, 332) in the insertion direction; a front wall provided with the liquid passage (35, 335); a rear wall positioned away from the front wall in the insertion direction, the liquid chamber (32, 33, 332) being positioned between the front wall and the rear wall in the insertion direction; a top wall (39, 339) positioned between the front wall and the rear wall in the insertion direction; and a bottom wall positioned between the front wall and the rear wall in the insertion direction and away from the top wall (39, 339) in the gravitational direction, the liquid chamber (32, 33, 332) being positioned between the top wall (39, 339) and the bottom wall in the gravitational direction; and a liquid chamber (32, 33, 332) storing liquid therein; a liquid passage (35, 335) extending from the liquid chamber (32, 33, 332) in the insertion direction; a front wall provided with the liquid passage (35, 335); a rear wall positioned away from the front wall in the insertion direction, the liquid chamber (32, 33, 332) being positioned between the front wall and the rear wall in the insertion direction; a top wall (39, 339) positioned between the front wall and the rear wall in the insertion direction; and a bottom wall positioned between the front wall and the rear wall in the insertion direction and away from the top wall (39, 339) in the gravitational direction, the liquid chamber (32, 33, 332) being positioned between the top wall (39, 339) and the bottom wall in the gravitational direction; and a lever (67, 267) supported by the casing (31, 331) and pivotable about a pivot axis between a first position and a second position, the lever comprising: a light-blocking portion (67A, 267A) configured to block or attenuate light traveling in a widthwise direction crossing the insertion direction and the gravitational direction, the light-blocking portion (67A, 267A) being positioned lower at the second position than at the first position; and a force-receiving portion (67C, 267D) positioned closer to the front wall than the light-blocking portion (67A, 267A) is to the front wall in the insertion direction, the pivot axis being positioned frontward of the light-blocking portion (67A, 267A) and rearward of the force-receiving portion (67C, 267D) in the insertion direction, a light-blocking portion (67A, 267A) configured to block or attenuate light traveling in a widthwise direction crossing the insertion direction and the gravitational direction, the light-blocking portion (67A, 267A) being positioned lower at the second position than at the first position; and a force-receiving portion (67C, 267D) positioned closer to the front wall than the light-blocking portion (67A, 267A) is to the front wall in the insertion direction, the pivot axis being positioned frontward of the light-blocking portion (67A, 267A) and rearward of the force-receiving portion (67C, 267D) in the insertion direction, characterized in that the lever (67, 267) is configured to pivot from the second position to the first position upon application of an external force to the force-receiving portion.