[en] The method of Pb and Sr isotope measurements at about 5 μm resolution was developed by using a high lateral resolution secondary ion mass spectrometer (NanoSIMS NS50). Since the both elements have radiogenic nuclides such as ²⁰⁶Pb, ²⁰⁷Pb, and ⁸⁷Sr, natural variations of isotopic ratios are large. It is possible to detect a meaningful variation in a terrestrial sample, even though the experimental error is relatively large. In the case of monazite U-Pb dating, a 4 nA O^- primary beam was used to sputter the sample and secondary positive ions were extracted for mass analysis using a Mattauch-Herzog geometry. The multi-collector system was modified to detect ¹⁴⁰Ce⁺, ²⁰⁴Pb⁺, ²⁰⁶Pb⁺, ²³⁸U¹⁶O⁺, and ²³⁸U¹⁶O₂⁺ ions simultaneously. Based on the monazite standard from North-Central Madagascar, we have determined the ²⁰⁶Pb/²³⁸U ratios of samples. ²⁰⁷Pb/²⁰⁶Pb ratios were measured by a magnet scanning with a single collector mode. 44 monazite grains extracted from a sedimentary rock in Taiwan were analyzed. Observed ages were consistent with the U-Th-Pb chemical ages by EPMA. Then NanoSIMS has been used to measure ⁸⁷Sr/⁸⁶Sr ratios in natural calcium carbonate samples. Multi-collector system was adjusted to detect ⁴³Ca⁺,⁸⁰Ca₂⁺, ⁸⁶Sr⁺, and ⁸⁷Sr⁺ ions at the same time. Magnetic field was scanning for the EM no.4 counter to detect ⁸⁵Rb⁺, ⁸⁶Sr⁺ and ⁸⁷Sr⁺, while the EM no.4b can measure ⁸⁶Sr⁺, ⁸⁷Sr⁺, and ⁸⁸Sr⁺, respectively. Repeated analyses of a coral skeleton standard (JCp-1) show that ⁸⁷Sr/⁸⁶Sr ratio agrees well with the seawater signature, after the series of corrections such as Ca dimer, ⁸⁷Rb, and a mass bias estimated by ⁸⁸Sr/⁸⁶Sr ratio. The method is applied to an otolith from ayu (Pleco-glossus altivelis altivelis) collected from the Yodo river, Japan. The spatial variation of ⁸⁷Sr/⁸⁶Sr ratios was consistent with amphidromous migration of the fish, namely, born in the lake and grown in the coastal sea and finally collected in a river. (author)