NOVELTY - The nozzle (11) has a discharge part (45) provided with a slit-shaped ejection opening (54) extended along longitudinal direction (X1). A pair of guide parts (46) is arranged at both ends of the ejection opening, respectively along longitudinal direction. The guide parts are provided with a pair of guide surfaces (66) arranged opposite to the longitudinal direction at intervals, respectively. A recessed part (68) indented from the guide surfaces is formed in each guide part. A guide groove is formed in the recessed part.    USE - Chemical slit nozzle for use in a substrate processing apparatus (claimed) such as cleaning apparatus, etching apparatus, resist coating apparatus and image development apparatus, for processing a substrate. Uses include but are not limited to a semiconductor wafer and a glass substrate of an LCD device, a substrate of a plasma display, a substrate of a field emission display, a substrate of an optical disk, a substrate of a magnetic disk, a substrate of a magneto optical disk, a substrate of a photo mask, a ceramic substrate and a substrate of a solar cell.    ADVANTAGE - The recessed part indented from the guide surfaces is formed in each guide part such that liquid discharged from the ejection opening is supplied to the recessed part and stored by the recessed part and moves to the guide surfaces, and the state in which the liquid is maintained at the guide surfaces is maintained, so that width of a liquid film can be stabilized, thus eliminating need for lengthening of the ejection opening, and hence suppressing enlargement of the nozzle.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a substrate processing apparatus.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of a chemical slit nozzle.'(Drawing includes non-English language text)'    Longitudinal direction (X1)    Nozzle (11)    Discharge part (45)    Pair of guide parts (46)    Slit-shaped ejection opening (54)    Pair of guide surfaces (66)    Recessed part (68)