Disclosed is a liquid detection unit having a liquid detection chamber, a detection portion including a detection space communicating with the liquid detection chamber via a through hole of a detection portion installation member and a piezoelectric sensor which detects remaining vibrations, and a movable member including a detection space sealing surface which is urged by an urging member and thus comes to abut against one surface of a detection portion installation member. The liquid detection chamber includes an abutting surface abutting against a second sealing surface being in contact with a first sealing surface of the movable member and the detection portion installation member. When a distance between the first sealing surface of the movable member to the detection space sealing surface is defined as L1 and a distance between the second sealing surface of the liquid detection chamber to the abutting surface is defined as L2, the relationship L1>L2 is satisfied.