There are provided a chip for micro chemical systems which can obviate the need of alignment at every measurement and can improve the measurement sensitivity and reduce the variation of measurement, and a micro chemical system using the chip. A thermal lens spectrometry system 10 comprises: a micro chemical chip 2 having a groove 1 into which a sample solution is injected; a rod lens 3 disposed on the micro chemical chip 2 at a predetermined spacing above the groove 1; a lens holder 9 disposed above the micro chemical chip 2; a securing section 4; an optical fiber 5; a ferrule 6 secured by the securing section 4 above the rod lens 3; a light source unit 7 connected to the optical fiber 5, and a detection device 8 disposed below the micro chemical chip 2. The securing section 4 comprises a seating 32 laid on the micro chemical chip 2, and a metal split sleeve 33 for fitting the ferrule 6 and the lens holder 9 at the outside thereof.