An image recording sheet used in electrophotographic imaging which comprises a paper sheet substrate coated with an image recording layer that takes on a probe penetration depth of 0.33 .mu.m or greater for a change in prove temperature from 50.degree. to 150.degree. C. when measuring the probe penetration depth on a scanning type thermal microscope having a thermal probe operative as both heater and position sensor that is made of a Pt alloy containing 10% of Rh and has a cantilever spring constant of 1 N/m, a diameter of 6 .mu.m and a curvature radius of 5 .mu.m at an extreme end thereof under a condition that the thermal prove is changed in temperature at a programming rate of 15.degree. C./sec within a programmed range of from a room temperature to 200.degree. C. under a load (weight)+20 nA in 4-split T-B (Top-Bottom) value.