A leak detection device is provided which comprises: in order to suppress effects of extraneous vibration and improve accuracy of leak detection, a first detection unit (6) which detects vibration in a first direction and output a first signal S1 representing a magnitude of the vibration in the first direction, the first detection unit (6) being installed to a pipe (2) in which fluid (5) flows; a second detection unit (7) which detects vibration in a second direction different from the first direction and output a second signal S2 representing a magnitude of the vibration in the second direction, the second detection unit (7) being installed to the pipe (2); and a signal processing unit (10) which performs an arithmetic operation processing using the first signal S1 and the second signal S2.