To provide a time measuring apparatus capable of accurately measuring a very short time interval between edges a signal has.

The tester 300 comprises a reference input signal generator 102 for generating a reference input signal having a specified period, a trigger pulse generator 104 for generating a trigger pulse, based on the reference input signal, and a clock generator 108 for generating a clock signal with the trigger pulse used as a trigger for starting oscillation. The clock generator 108 comprises a time measuring unit 308 having a clock source 204 which stops from oscillating upon receipt of the trigger pulse and resumes a new oscillation to generate a new clock signal.