A fluid level detection apparatus comprising: - a vibrator configured to apply a vibration to a container that contains a fluid; - a vibration sensor configured to detect a vibration wave that is generated by the vibrator and propagates through the container ; and - a controller configured to control an operation of the vibrator and perform arithmetic processing on a detection signal obtained from the vibration sensor , - the vibrator and the vibration sensor being provided on an outer wall surface of the container at respective positions that interpose, from above and below, a fluid level of the fluid provided in the container , - the controller being configured to calculate a height of the fluid level, on a basis of the vibration wave detected by the vibration sensor , characterised by further comprising a temperature sensor configured to measure a temperature of the outer wall of the container , wherein the controller is configured to calculate the temperature of the fluid , wherein the controller is further configured to cause the vibrator to generate, as the vibration, an ultrasonic vibration that covers a predetermined frequency range, and wherein the controller 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 , 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 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 configured to apply a vibration to a container that contains a fluid; - a vibration sensor configured to detect a vibration wave that is generated by the vibrator and propagates through the container ; and - a controller configured to control an operation of the vibrator and perform arithmetic processing on a detection signal obtained from the vibration sensor , - the vibrator and the vibration sensor being provided on an outer wall surface of the container at respective positions that interpose, from above and below, a fluid level of the fluid provided in the container , - the controller being configured to calculate a height of the fluid level, on a basis of the vibration wave detected by the vibration sensor , further comprising a temperature sensor configured to measure a temperature of the outer wall of the container , wherein the controller is configured to calculate the temperature of the fluid , wherein the controller is further configured to cause the vibrator to generate, as the vibration, an ultrasonic vibration that covers a predetermined frequency range, and wherein the controller 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 , 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 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. <EOS>