A state monitoring system (100) for a rotary machine is provided with a sensor head (2), a preamplifier (4), a main body unit (6), and a temperature sensor (23), which is provided to the preamplifier(4), and which outputs an ambient temperature value by measuring the ambient temperature of a motor (1). The sensor head (2) includes: an acceleration sensor (11), which measures vibration of the motor, and outputs a vibration value; and a temperature sensor (12), which measures the surface temperature of the motor (1), and outputs a rotary machine surface temperature value. The main body unit (6)is provided with: a processing unit (31) that determines the state of the motor (1) by comparing a current vibration value with a determination threshold value; a display unit (7) that displays the vibration value, the rotary machine surface temperature value, and the ambient temperature value; an output unit (35) that outputs determination results obtained from the processing unit (31); and a communication unit (33), which receives the determination threshold value from a high-order system, and transmits the current vibration value and the determination results to the high-order system.