To inform a user of damage of a product with a temperature sensor using a shape memory alloy because the temperature sensor made of the shape memory alloy and a separation member comprising a strip unit having an aggregate of many staples is separated by a stapler, is fixed to a solid container made of glass or the like, and has a second shape below a critical temperature, but, above or at the critical temperature, the temperature sensor has a first shape, is separated from the product, and displays alarm information of the product, and to provide a manufacturing method of the temperature sensor.

This temperature sensor 10 using the shape memory alloy comprises the strip unit 2 having the aggregate of U-shaped individual staples having both legs 3 and 4, and has a predetermined first shape at the critical temperature or more or has an arbitrary second shape at the critical temperature or less.