A vacuum insulator (10) includes: a core (13); a pressure sensor (51) that detects a pressure; a transmitter (52) that transmits, by wireless communication, the detected pressure detected by the pressure sensor (51); a power feeder (53) that feeds electric power to the pressure sensor (51) and the transmitter (52); and an outer skin (14), an inside of which is decompressed, the outer skin (14) accommodating therein the core (13), the pressure sensor (51), the transmitter (52), and the power feeder (53), the outer skin (14) having gas barrier capability.