A fluid level detection apparatus comprising: - a vibrator (11, 41) configured to apply a vibration to a container (23, 52) that contains a fluid; - a vibration sensor (12, 42) configured to detect a vibration wave that is generated by the vibrator (11, 41) and propagates through the container (23, 52); and - a controller (14, 44) configured to control an operation of the vibrator (11, 41) and perform arithmetic processing on a detection signal obtained from the vibration sensor (12, 42), - the vibrator (11, 41) and the vibration sensor (12, 42) being provided on an outer wall surface of the container (23, 52) at respective positions that interpose, from above and below, a fluid level of the fluid provided in the container (23, 52), - the controller (14, 44) being configured to calculate a height of the fluid level, on a basis of the vibration wave detected by the vibration sensor (12, 42), characterised by further comprising a temperature sensor configured to measure a temperature of the outer wall of the container (23, 52), wherein the controller (14, 44) is configured to calculate the temperature of the fluid, wherein the controller (14, 44) is further configured to cause the vibrator (11, 41) to generate, as the vibration, an ultrasonic vibration that covers a predetermined frequency range, and wherein the controller (14, 44) is configured to calculate, as the height of the fluid level, a nominal value of the height of the fluid level on a basis of a high frequency component in the vibration wave detected by the vibration sensor (12, 42), and correct the nominal value by an amount corresponding to a change in temperature of the fluid on a basis of a low frequency component in the vibration wave detected by the vibration sensor (12, 42) and the temperature of the fluid, the high frequency component being higher than a first predetermined frequency, the low frequency component being lower than a second predetermined frequency, and the controller being configured to apply a filtering process to the vibration wave to extract the high frequency component and the low frequency component. - a vibrator (11, 41) configured to apply a vibration to a container (23, 52) that contains a fluid; - a vibration sensor (12, 42) configured to detect a vibration wave that is generated by the vibrator (11, 41) and propagates through the container (23, 52); and - a controller (14, 44) configured to control an operation of the vibrator (11, 41) and perform arithmetic processing on a detection signal obtained from the vibration sensor (12, 42), - the vibrator (11, 41) and the vibration sensor (12, 42) being provided on an outer wall surface of the container (23, 52) at respective positions that interpose, from above and below, a fluid level of the fluid provided in the container (23, 52), - the controller (14, 44) being configured to calculate a height of the fluid level, on a basis of the vibration wave detected by the vibration sensor (12, 42), further comprising a temperature sensor configured to measure a temperature of the outer wall of the container (23, 52), wherein the controller (14, 44) is configured to calculate the temperature of the fluid, wherein the controller (14, 44) is further configured to cause the vibrator (11, 41) to generate, as the vibration, an ultrasonic vibration that covers a predetermined frequency range, and wherein the controller (14, 44) is configured to calculate, as the height of the fluid level, a nominal value of the height of the fluid level on a basis of a high frequency component in the vibration wave detected by the vibration sensor (12, 42), and correct the nominal value by an amount corresponding to a change in temperature of the fluid on a basis of a low frequency component in the vibration wave detected by the vibration sensor (12, 42) and the temperature of the fluid, the high frequency component being higher than a first predetermined frequency, the low frequency component being lower than a second predetermined frequency, and the controller being configured to apply a filtering process to the vibration wave to extract the high frequency component and the low frequency component.