An apparatus for measuring on-chip characteristics in a semiconductor circuit is provided. The apparatus for measuring the on-chip characteristics includes an oscillation unit, a timing test unit, and a selection unit. The oscillation unit is configured to selectively output a first oscillation signal responsive to a first control signal. The timing test unit is configured to generate a second oscillation signal using an input clock signal, generate a pulse from the second oscillation signal responsive to a second control signal, and determine whether an operating time violation has occurred based on a comparison of the second oscillation signal and the pulse. The selection unit is configured to select one of the output of the oscillation unit and the output of the timing test unit responsive to a test mode signal. The apparatus is configured to measure an on-chip delay using a period of the first oscillation, or to measure a timing margin of the semiconductor circuit using an output of the timing test unit, based on an output of the selection unit.